Lead-free low-melting glass composition, low-temperature sealing glass frit, low-temperature sealing glass paste, conductive material, and conductive glass paste containing glass composition, and glass-sealed component and electric/electronic component prepared using the same

ABSTRACT

Disclosed is an Ag 2 O—V 2 O 5 —TeO 2  lead-free low-melting glass composition that is prevented or restrained from crystallization so as to soften and flow more satisfactorily at a low temperature. This lead-free low-melting glass composition contains a principal component; and an additional component. The principal component includes a vanadium oxide, a tellurium oxide and a silver oxide. The additional component includes at least one selected from the group consisting of yttrium oxide and lanthanoid oxides. A content of the additional component is 0.1 to 3.0 mole percent in terms of oxide. The additional component preferably contains at least one selected from Y 2 O 3 , La 2 O 3 , CeO 2 , Er 2 O 3 , and Yb 2 O 3  in a content of 0.1 to 2.0 mole percent in terms of oxide. The additional component particularly effectively contains at least one of Y 2 O 3  and La 2 O 3  in a total content of 0.1 to 1.0 mole percent.

CLAIM OF PRIORITY

The present application claims priority from Japanese Patent applicationserial No. 2014-175580, filed on Aug. 29, 2014, the content of which ishereby incorporated by reference into this application.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to lead-free low-melting glasscompositions. Specifically, the present invention relates to a lead-freelow-melting glass composition that is prevented or restrained fromcrystallization and can thereby soften and flow satisfactorily at alower temperature. The present invention also relates to alow-temperature sealing glass frit, a low-temperature sealing glasspaste, a conductive material, and a conductive glass paste, each ofwhich contains the lead-free low-melting glass composition; and to aglass-sealed component and an electrical/electronic component preparedby using any of them.

Description of Related Art

In some articles, a low-temperature sealing glass frit including alow-melting glass composition and low-thermal-expansion ceramicparticles is used typically for sealing and/or bonding. The articles areexemplified by vacuum-insulating double glass panels applied typicallyto window panes; display panels such as plasma display panels, organicelectroluminescent display panels, and fluorescent display tubes; andelectrical/electronic components such as quartz resonators, IC ceramicpackages, and semiconductor sensors. The low-temperature sealing glassfrit is often applied in the form of a low-temperature sealing glasspaste. The low-temperature sealing glass paste is applied typically by ascreen process printing or dispensing, dried, and fired for use insealing and/or bonding. Upon the sealing and/or bonding, the low-meltingglass composition contained in the low-temperature sealing glass frit orin the corresponding low-temperature sealing glass paste softens, flows,and thereby comes in intimate contact with a member to be sealed and/orto be bonded.

Likewise, a conductive material including a low-melting glasscomposition and metal particles is used to form an electrode and/or aninterconnection in many electrical/electronic components such as solarcells, image display devices, multilayer capacitors, quartz resonators,LEDs (light-emitting diodes), and multilayered circuit boards. Theconductive material is also used as a conductive bonding material forconduction. The conductive material is often applied in the form of aconductive glass paste, as with the low-temperature sealing glass frit.The conductive glass paste is applied typically by a screen processprinting or dispensing, dried, and fired to form an electrode, aninterconnection, and/or a conductive junction. Also upon the formation,the low-melting glass composition contained in the conductive materialor in the corresponding conductive glass paste softens, flows, andthereby allows the metal particles to sinter or to be brought intointimate contact with a substrate.

The low-melting glass compositions to be contained in thelow-temperature sealing glass frit or the corresponding low-temperaturesealing glass paste, as well as the conductive material and thecorresponding conductive glass paste have often employed PbO—B₂O₃low-melting glass compositions containing a very large amount of leadoxide. The PbO—B₂O₃ low-melting glass compositions have a low softeningpoint of 350° C. to 400° C., can soften and flow satisfactorily at 400°C. to 450° C., and still have relatively high chemical stability. The“softening point” refers to a second endothermic peak temperature asdetermined by a differential thermal analysis “DTA”.

However, more safe materials have been demanded in the electrical andelectronic equipment industry in accordance with the recent global trendtoward green procurement/green design. Typically, the Directive on therestriction of the use of certain hazardous substances in electrical andelectronic equipment (RoHS directive) took effective on 1 Jul. 2006 bythe European Union. The RoHS directive restricts the use of sixhazardous materials, i.e., lead, mercury, cadmium, hexavalent chromium,polybrominated biphenyls, and polybrominated diphenyl ether.

The PbO—B₂O₃ low-melting glass compositions contain a large amount oflead that is restricted by the RoHS directive and are hardly applied tolow-temperature sealing glass frits, corresponding low-temperaturesealing glass pastes, conductive materials, and corresponding conductivepastes. Thereby, the development of novel lead-free low-melting glasscompositions has proceeded. In addition, strong demands have been madeto develop lead-free low-melting glass compositions that soften and flowat a lower temperature as compared with the PbO—B₂O₃ low-melting glasscompositions and still have good chemical stability. These demands havebeen made so as to allow various glass-sealed components andelectrical/electronic components to less undergo thermal damage (to havehigher functions) and to have better productivity (with reduced takttime). Specifically, demands have been made to provide lead-freelow-melting glass compositions that soften and flow at a temperature of350° C. or lower, preferably 300° C. or lower, and are applicabletypically to sealing and/or bonding or to the formation ofelectrodes/interconnections and conductive junctions.

Japanese Patent Application Laid-Open No. 2013-32255 (PatentLiterature 1) discloses a lead-free low-melting glass composition. Theglass composition contains, in terms of oxides, 10 to 60 mass percent ofAg₂O, 5 to 65 mass percent of V₂O₅, and 15 to 50 mass percent of TeO₂.The glass composition contains Ag₂O, V₂O₅, and TeO₂ in a total contentof 75 mass percent to less than 100 mass percent, with the remainderbeing at least one of P₂O₅, BaO, K₂O, WO₃, Fe₂O₃, MnO₂, Sb₂O₃, and ZnOin a content of greater than 0 mass percent to 25 mass percent. Thepatent literature mentions that the Ag₂O—V₂O₅—TeO₂ lead-free low-meltingglass composition has a low softening point of 320° C. or lower, softensand flows at a lower temperature as compared with the conventionalPbO—B₂O₃ low-melting glass compositions, and still has good chemicalstability, where the softening point is determined from the secondendothermic peak temperature by the differential thermal analysis (DTA).In addition, Patent Literature 1 proposes a low-temperature sealingglass frit, a low-temperature sealing glass paste, a conductivematerial, and a conductive glass paste each containing theAg₂O—V₂O₅—TeO₂ lead-free low-melting glass composition; and anelectrical/electronic component prepared using any of them.

SUMMARY OF THE INVENTION

The present invention provides, in an embodiment, a lead-freelow-melting glass composition containing a principal component; and anadditional component, the principal component including a vanadiumoxide, a tellurium oxide and a silver oxide, the additional componentincluding at least one selected from the group consisting of yttriumoxide and lanthanoid oxides, in which a content of the additionalcomponent is 0.1 to 3.0 mole percent in terms of oxide.

The present invention allows a lead-free low-melting glass compositioncontaining a vanadium oxide, a tellurium oxide, and a silver oxide tohave a smaller crystallization tendency and to be prevented orrestrained from crystallization upon heating-firing. This provides alead-free low-melting glass composition that softens and flows moresatisfactorily at a temperature of 350° C. or lower, and preferably 300°C. or lower, still has excellent chemical stability, and meets the RoHSdirective.

The lead-free low-melting glass composition according to the embodimentof the present invention, when combined with ceramic particles and/ormetal particles, can give a low-temperature sealing glass frit, alow-temperature sealing glass paste, a conductive material, and aconductive glass paste each of which can enjoy advantageous effects ofthe lead-free low-melting glass composition according to the embodimentof the present invention.

The low-temperature sealing glass frit, low-temperature sealing glasspaste, conductive material, and conductive paste each containing thelead-free low-melting glass composition according to the embodiment ofthe present invention, when applied, can give a glass-sealed componentand an electrical/electronic component that includes anelectrode/interconnection or a conductive junction. The glass-sealedcomponent, the electrode/interconnection, and the conductive junctionare sealed, bonded, or formed at a firing temperature of 350° C. orlower, and preferably 300° C. or lower. These components are obtainedafter consideration of influence on the environmental burden.Specifically, use of the lead-free low-melting glass compositionaccording to the embodiment of the present invention allows theglass-sealed component and the electrical/electronic component to lessundergo thermal damage (to have higher functions), to have betterproductivity (to require reduced takt time) and better reliability(chemical stability at certain level), and to put less burden on theenvironment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a glass-specific differential thermal analysis (DTA) curve ona typical glass formulation;

FIG. 2 is a schematic diagram illustrating how to prepare a bondedarticle for shear stress measurement;

FIG. 3 is a graph illustrating how a contact resistance varies dependingon the contents of a lead-free low-melting glass composition accordingto an embodiment of the present invention and Ag particles contained ina conductive material, where the contact resistance is determined in anAl/Al bonded article, a Ag/Ag bonded article, and a Cu/Cu bonded articleeach of which is assembled and bonded using the conductive material;

FIG. 4 is a graph illustrating how a contact resistance varies dependingon the contents of the lead-free low-melting glass composition accordingto the embodiment of the present invention and Cu particles contained ina conductive material, where the contact resistance is determined in anAl/Al bonded article, a Ag/Ag bonded article, and a Cu/Cu bonded articleeach of which is assembled and bonded using the conductive material;

FIG. 5 is a graph illustrating how a contact resistance varies dependingon the contents of the lead-free low-melting glass composition accordingto the embodiment of the present invention and Al particles contained ina conductive material, where the contact resistance is determined in anAl/Al bonded article, a Ag/Ag bonded article, and a Cu/Cu bonded articleeach of which is assembled and bonded using the conductive material;

FIG. 6 is a graph illustrating how a contact resistance varies dependingon the contents of the lead-free low-melting glass composition accordingto the embodiment of the present invention and Sn particles contained ina conductive material, where the contact resistance is determined in anAl/Al bonded article, a Ag/Ag bonded article, and a Cu/Cu bonded articleeach of which is assembled and bonded using the conductive material;

FIG. 7 is a schematic perspective view of an interconnection pattern forinterconnect resistance and peel test measurements of formedelectrodes/interconnections;

FIG. 8 is a graph illustrating how an interconnect resistance variesdepending on the contents of the lead-free low-melting glass compositionaccording to the embodiment of the present invention and Ag particlescontained in a conductive material, where the interconnect resistance isdetermined in an electrode/interconnection formed using the conductivematerial;

FIG. 9A is a schematic plan view of a vacuum-insulating double glasspanel prepared according to an embodiment of the present invention;

FIG. 9B is a cross-sectional view taken along the line A-A of FIG. 9A;

FIG. 10A is a schematic plan view illustrating a step of a method forproducing the vacuum-insulating double glass panel of FIG. 9A;

FIG. 10B is a cross-sectional view taken along the line A-A of FIG. 10A;

FIG. 11A is a schematic plan view illustrating another step of themethod for producing the vacuum-insulating double glass panel of FIG.9A;

FIG. 11B is a cross-sectional view taken along the line A-A of FIG. 11A;

FIG. 12 is a schematic cross-sectional view illustrating yet anotherstep of the method for producing the vacuum-insulating double glasspanel of FIG. 9A;

FIG. 13 is a graph illustrating a sealing temperature profile in thestep of FIG. 12 of the method for producing the vacuum-insulating doubleglass panel;

FIG. 14A is a schematic plan view of an organic light-emitting diode(OLED) display prepared according to an embodiment of the presentinvention;

FIG. 14B is a cross-sectional view taken along the line A-A of FIG. 14A;

FIG. 15A is a schematic plan view illustrating a step of a method forproducing the OLED display of FIGS. 14A and 14B;

FIG. 15B is a cross-sectional view taken along the line A-A of FIG. 15A;

FIG. 16A is a schematic plan view illustrating another step of themethod for producing the OLED display of FIGS. 14A and 14B;

FIG. 16B is a cross-sectional view taken along the line A-A of FIG. 16A;

FIG. 17 is a schematic cross-sectional view illustrating yet anotherstep of the method for producing the OLED display of FIGS. 14A and 14B;

FIG. 18A is a schematic plan view of a light-receiving surface of asolar cell prepared according to an embodiment of the present invention;

FIG. 18B is a back view of the light-receiving surface of the solar cellof FIG. 18A;

FIG. 18C is a cross-sectional view taken along the line A-A of FIG. 18A;

FIG. 19A is a schematic cross-sectional view illustrating a step of amethod for producing a quartz resonator package according to anembodiment of the present invention;

FIG. 19B is a schematic cross-sectional view illustrating another stepof the method for producing a quartz resonator package according to theembodiment of the present invention;

FIG. 19C is a schematic cross-sectional view illustrating yet anotherstep of the method for producing a quartz resonator package according tothe embodiment of the present invention;

FIG. 19D is a schematic cross-sectional view illustrating still anotherstep of the method for producing a quartz resonator package according tothe embodiment of the present invention;

FIG. 19E is a schematic cross-sectional view illustrating another stepof the method for producing a quartz resonator package according to theembodiment of the present invention;

FIG. 19F is a schematic cross-sectional view illustrating yet anotherstep of the method for producing a quartz resonator package according tothe embodiment of the present invention; and

FIG. 19G is a schematic cross-sectional view of a quartz resonatorpackage produced by the method illustrated in FIGS. 19A to 19F.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The Ag₂O—V₂O₅—TeO₂ lead-free low-melting glass composition disclosed inPatent Literature 1 certainly has a lower softening point as comparedwith the conventional PbO—B₂O₃ low-melting glass compositions, but has atendency to crystallize and thereby softens and flows unsatisfactorilydue to the crystallization tendency upon heating-firing. Specifically,with insufficient consideration on the crystallization tendency, theglass composition disadvantageously softens and flows unsatisfactorilyat a low temperature of 350° C. or lower, and preferably 300° C. orlower. Assume that the glass composition is mixed withlow-thermal-expansion ceramic particles or metal particles or is formedinto a paste upon usage. In this case, the glass composition moresignificantly undergoes crystallization. This causes the glasscomposition to be hardly expanded into low-temperature sealing glassfrits, low-temperature sealing glass pastes, conductive materials, andconductive pastes and to be hardly applied to glass-sealed componentsand electrical/electronic components obtained using any of them.

It is an object of the present invention to prevent or restrain thecrystallization of a Ag₂O—V₂O₅—TeO₂ lead-free low-melting glasscomposition and to thereby provide a lead-free low-melting glasscomposition that satisfactorily softens and flows at a temperature of350° C. or lower, and preferably 300° C. or lower. It is another objectof the present invention to provide, based on the above, a lead-freelow-melting glass composition that has a smaller crystallizationtendency even when mixed with low-thermal-expansion ceramic particles ormetal particles, or formed into a paste. It is yet another object of thepresent invention to expand the lead-free low-melting glass compositionso as to provide a low-temperature sealing glass frit, a low-temperaturesealing glass paste, a conductive material, and a conductive glasspaste; and a glass-sealed component and an electrical/electroniccomponent obtained using any of them.

The present invention provides a lead-free low-melting glass compositionthat contains a vanadium oxide, a tellurium oxide, and a silver oxideand further contains an additional component including at least oneselected from yttrium oxide and lanthanoid oxides. The lead-freelow-melting glass composition contains the additional component in acontent in terms of oxide of 0.1 to 3.0 mole percent. As used herein theterm “lead-free” also refers to and includes one containing therestricted materials in contents at the restricted levels or lower asrestricted in the RoHS directive (that took effective on 1 Jul. 2006).The restricted level is 1000 ppm or less for lead (Pb).

The glass composition may contain, as the additional component, at leastone selected from the group consisting of Y₂O₃, La₂O₃, CeO₂, Er₂O₃, andYb₂O₃ in a content (total content) in terms of oxide of 0.1 to 2.0 molepercent. In particular, the glass composition may effectively contain atleast one of Y₂O₃ and La₂O₃ as the additional component. The glasscomposition more preferably contains the additional component in thecontent of 0.1 to 1.0 mole percent.

The lead-free low-melting glass composition according to the embodimentof the present invention preferably contains V₂O₅, TeO₂, and Ag₂O in atotal content in terms of oxide of 85 mole percent or more andpreferably has contents of TeO₂ and Ag₂O each 1 to 2 times as much asthe content of V₂O₅. The glass composition preferably further containsat least one of BaO, WO₃, and P₂O₅ in a content (total content) in termsof oxide of 13 mole percent or less.

The lead-free low-melting glass composition according to the embodimentof the present invention may have a softening point of 280° C. or lower,where the softening point is determined by a differential thermalanalysis (DTA) as a second endothermic peak temperature. The glasscomposition may have a crystallization onset temperature higher than thesecond endothermic peak temperature (softening point) by 60° C. or more,where the crystallization onset temperature is determined by thedifferential thermal analysis (DTA).

The present invention provides, in another embodiment, a low-temperaturesealing glass frit containing 40 to 100 volume percent of the lead-freelow-melting glass composition and 0 to 60 volume percent oflow-thermal-expansion ceramic particles. Herein, the low-temperaturesealing glass frit contains the lead-free low-melting glass compositionand the low-thermal-expansion ceramic particles. Hence, the content ofthe lead-free low-melting glass composition is actually less than 100volume percent, and the content of the low-thermal-expansion ceramicparticles is actually more than 0 volume percent. The same applies inthe following numerical ranges.

The low-thermal-expansion ceramic particles preferably include at leastone selected from the group consisting of zirconium phosphate tungstate(Zr₂ (WO₄) (PO₄)₂), quartz glass (SiO₂), zirconium silicate (ZrSiO₄),aluminum oxide (Al₂O₃), mullite (3Al₂O₃.2SiO₂), and niobium oxide(Nb₂O₅). In particular, the low-thermal-expansion ceramic particles arepreferably particles of zirconium phosphate tungstate (Zr₂(WO₄) (PO₄)₂)and/or particles of a compound containing mainly zirconium phosphatetungstate (Zr₂(WO₄) (PO₄)₂). The glass frit effectively contains 30 to50 volume percent of the low-thermal-expansion ceramic particles.

The low-temperature sealing glass frit may be prepared from alow-temperature sealing glass paste that contains the lead-freelow-melting glass composition according to the embodiment of the presentinvention in the form of particles, low-thermal-expansion ceramicparticles, and a solvent. In the low-temperature sealing glass paste,the low-thermal-expansion ceramic particles preferably include at leastone selected from the group consisting of zirconium phosphate tungstate(Zr₂(WO₄)(PO₄)₂), quartz glass (SiO₂), zirconium silicate (ZrSiO₄),aluminum oxide (Al₂O₃), mullite (3Al₂O₃.2SiO₂), and niobium oxide(Nb₂O₅), and the solvent preferably includes α-terpineol and/ordiethylene glycol n-butyl ether acetate (e.g., Butyl CARBITOL Acetate).In particular, the low-thermal-expansion ceramic particles effectivelyinclude zirconium phosphate tungstate (Zr₂(WO₄) (PO₄)₂) and/or acompound containing mainly zirconium phosphate tungstate (Zr₂(WO₄)(PO₄)₂), and the solvent effectively includes α-terpineol.

The present invention provides, in yet another embodiment, a conductivematerial containing 5 to 100 volume percent of the lead-free low-meltingglass composition, and 0 to 95 volume percent of metal particles. Theconductive material preferably contains, as the metal particles, atleast one selected from the group consisting of silver (Ag), silveralloys, copper (Cu), copper alloys, aluminum (Al), aluminum alloys, tin(Sn), and tin alloys. In particular, the conductive material preferablycontains at least one of silver (Ag) and aluminum (Al) as the metalparticles. The content of the metal particles is effectively 10 to 90volume percent.

The conductive material may be formed from a conductive glass paste thatcontains the lead-free low-melting glass composition according to theembodiment of the present invention in the form of particles, and asolvent. The conductive glass paste may further contain metal particles.The metal particles may include at least one selected from the groupconsisting of silver (Ag), silver alloys, copper (Cu), copper alloys,aluminum (Al), aluminum alloys, tin (Sn), and tin alloys. The solventpreferably includes α-terpineol and/or diethylene glycol n-butyl etheracetate. In an effective embodiment, the metal particles may includesilver (Ag) and/or aluminum (Al), and the solvent may includeα-terpineol.

The present invention provides, in still another embodiment, aglass-sealed component including a seal portion containing a lead-freelow-melting glass phase. The seal portion contains 40 to 100 volumepercent of the lead-free low-melting glass phase. The lead-freelow-melting glass phase may be derived from the lead-free low-meltingglass composition according to the embodiment of the present invention.The glass-sealed component can be effectively expanded typically intovacuum-insulating double glass panels and display panels.

The present invention provides, in another embodiment, anelectrical/electronic component including at least one unit selectedfrom electrodes, interconnections, and conductive junctions, where theat least one unit contains the lead-free low-melting glass phase. Theunit contains 5 to 100 volume percent of the lead-free low-melting glassphase and 0 to 95 volume percent of metal particles. Theelectrical/electronic component can be effectively expanded typicallyinto solar cells, image display devices, multilayer capacitors, quartzresonators, LEDs (light-emitting diodes), and multilayered circuitboards.

The present invention will be illustrated in further detail withreference to certain embodiments thereof and the attached drawings. Itshould be noted, however, that the embodiments are never construed tolimit the scope of the present invention; and that various combinations,changes, modifications, and improvements are possible without deviatingfrom the spirit and scope of the present invention.

(Glass Composition)

In general, a low-melting glass composition more satisfactorily softensand flows at a low temperature with a decreasing characteristictemperature (e.g., glass transition point, yield point, or softeningpoint). In contrast, the low-melting glass composition has a highercrystallization tendency, becomes more susceptible to crystallizationupon heating-firing, and, contrarily, softens and flows unsatisfactorilyat a low temperature with an excessively low characteristic temperature.In addition, a glass having a lower characteristic temperature hasinferior chemical stability such as water resistance and acidresistance. This glass also has a tendency to put a larger burden on theenvironment. Typically, with an increasing content of hazardous PbO, theconventional PbO—B₂O₃ low-melting glass compositions can have lowercharacteristic temperatures, but have a higher crystallization tendencyand lower chemical stability, and put larger burden on the environment.

The present inventors made intensive investigations on a glasscomposition that is a low-melting glass composition containingapproximately no lead, but can soften and flow satisfactorily at a lowertemperature as compared with the conventional PbO—B₂O₃ low-melting glasscompositions, and still has good chemical stability. As a result, thepresent inventors have found that a novel low-melting glass compositionmeets the requirements simultaneously. The present invention has beenmade based on these findings.

As described above, the lead-free low-melting glass compositionaccording to the embodiment of the present invention is a lead-freelow-melting glass composition that contains a vanadium oxide, atellurium oxide, and a silver oxide as principal components, and furthercontains 0.1 to 3.0 mole percent of an additional component including atleast one selected from yttrium oxide and lanthanoid oxides. The presentinventors have found that the lead-free low-melting glass compositioncan have a smaller crystallization tendency, when combined with a smallamount of at least one selected from yttrium oxide and lanthanoidoxides. The glass composition effectively contains the additionalcomponent in the content within the range of 0.1 to 3.0 mole percent.The glass composition may hardly effectively have a smallercrystallization tendency, if containing the additional component in thecontent less than 0.1 mole percent. In contrast, the glass compositionmay suffer from higher characteristic temperatures such as softeningpoint, or may have a higher crystallization tendency contrarily, ifcontaining the additional component in the content greater than 3.0 molepercent. Of the yttrium oxide and lanthanoid oxides, Y₂O₃, La₂O₃, CeO₂,Er₂O₃, and Yb₂O₃ are more effective for the reduction of crystallizationtendency. The glass composition may effectively contain at least one ofthese oxides in the content of 0.1 to 2.0 mole percent. Among them, theglass composition may particularly effectively contain at least one ofY₂O₃ and La₂O₃ in the content of 0.1 to 1.0 mole percent.

Next, it will be illustrated how the vanadium oxide, tellurium oxide andsilver oxide which are the principal components act in the lead-freelow-melting glass composition. The silver oxide is contained so as toallow the glass composition to have lower characteristic temperaturessuch as glass transition point, yield point, and softening point and tohave better chemical stability. The vanadium oxide is contained so as toprevent the silver oxide from reduction and from precipitating as metalsilver upon glass production. The silver oxide contained as a glasscomponent may fail to effectively offer characteristic temperatures atdesired low levels unless it is present in the form of silver ion in theglass. The glass composition can offer lower characteristic temperatureswith an increasing content of the silver oxide, i.e., with an increasingamount of silver ions in the glass. However, this requires a highercontent of the vanadium oxide so as to prevent or restrain theprecipitation of metal silver. The glass can contain a monovalent silverion in a number of up to 2 per one pentavalent vanadium ion upon itsproduction. The tellurium oxide acts as a vitrification component so asto cause vitrification upon glass production. The glass compositionfails to form glass, if containing no tellurium oxide. However, thetetravalent tellurium ion can effectively act when contained in a numberup to 1 per one pentavalent vanadium ion. If the number is greater than1, a compound between tellurium and silver may precipitate.

In consideration of the above-described functions and actions of thevanadium oxide, tellurium oxide, and silver oxide, the lead-freelow-melting glass composition according to the embodiment of the presentinvention preferably has such a basic formulation that the total contentof V₂O₅, TeO₂, and Ag₂O in terms of oxide is 85 mole percent or more,and the contents of TeO₂ and Ag₂O are each 1 to 2 times as much as thecontent of V₂O₅. Disadvantageously, if the glass composition has a basicformulation lower than or higher than the range, the glass compositionmay cause a metal silver precipitation upon glass production, may haveless effectively lowered characteristic temperatures, may undergo asignificant crystallization upon heating-firing, or may have an inferiorchemical stability. In addition, the glass composition may furthercontain a secondary component including at least one of BaO, WO₃, andP₂O₅ in the content in terms of the oxides of 13 mole percent or less.This is effective for the lead-free low-melting glass compositionaccording to the embodiment of the present invention to form glass in ahomogeneous vitreous state (amorphous state) and for the resulting glassto have a smaller crystallization tendency. However, the glasscomposition may have higher characteristic temperatures, if containingthe secondary component in the content greater than 13 mole percent.

As having the above-mentioned configuration, the lead-free low-meltingglass composition according to the embodiment of the present inventioncan have a softening point of 280° C. or lower, where the softeningpoint is determined by the differential thermal analysis (DTA) as asecond endothermic peak temperature. In addition, the glass compositioncan have a crystallization onset temperature higher than the secondendothermic peak temperature (softening point) by 60° C. or more, wherethe crystallization onset temperature is determined by the DTA. Thelead-free low-melting glass composition according to the embodiment ofthe present invention preferably has a lower softening point and, incontrast, a higher crystallization onset temperature. This allows theglass composition to soften and flow at a low temperature moresatisfactorily. This is preferred so as to expand the glass compositioninto low-temperature sealing glass frits, low-temperature sealing glasspastes, conductive materials, and conductive pastes and to apply them toglass-sealed components and electrical/electronic components. However,conventional low-melting glass compositions may often suffer from alower crystallization onset temperature, when designed to have a lowersoftening point.

The characteristic temperatures in the present invention will bedescribed below. The characteristic temperatures herein are measured bythe differential thermal analysis (DTA). FIG. 1 is an exemplary DTAcurve specific to glass on atypical glass formulation. Measurement ofglass by the DTA is generally performed using glass particles having aparticle diameter of about several tens of micrometers with high purityaluminum oxide (α-Al₂O₃) particles as a reference standard. Themeasurement may be performed in the air at a rate of temperature rise of5° C. per minute. As illustrated in FIG. 1, the onset temperature of afirst endothermic peak is defined as the glass transition point T_(g);the peak temperature of the first endothermic peak is defined as theyield point (deformation point) M_(g); the second endothermic peaktemperature is defined as the softening point T_(s); and the onsettemperature of the exothermic crystallization peak is defined as thecrystallization onset temperature T_(cry). The characteristictemperatures are each generally determined by the tangent method. Thecharacteristic temperatures T_(g), M_(g), and T_(s) are defined by theglass viscosity and are temperatures respectively corresponding toviscosities of 10^(13.3) poise, 10^(11.0) poise, and 10^(7.65) poise.The crystallization tendency may be determined by the crystallizationonset temperature T_(cry) and the size of the exothermic crystallizationpeak, i.e., the amount of heat liberated by crystallization. It can besaid that glass is less susceptible to crystallization when having ahigher crystallization onset temperature T_(cry), i.e., a largerdifference between the softening point T_(s) and the crystallizationonset temperature T_(cry) and having a smaller amount of heat liberatedby crystallization.

Assume that a low-melting glass composition is used to seal and/or bondvarious parts or components or to form electrodes/interconnections andconductive junctions. In this process, the low-melting glass compositionis fired generally frequently at a preset temperature higher than thesoftening point T_(s) by about 20° C. to about 60° C., although thefiring temperature may vary depending typically on the type, content,and particle diameter of the contained low-thermal-expansion ceramicparticles or metal particles, and on the firing conditions such as rateof temperature rise, atmosphere, and pressure. The low-melting glasscomposition has to satisfactorily soften and flow at that firingtemperature. It is therefore very important to minimize thecrystallization of the low-melting glass composition at the firingtemperature.

(Low-Temperature Sealing Glass Frit and Low-Temperature Sealing GlassPaste)

The low-temperature sealing glass frit according to an embodiment of thepresent invention contains 40 to 100 volume percent of the lead-freelow-melting glass composition according to the embodiment of the presentinvention, and 0 to 60 volume percent of low-thermal-expansion ceramicparticles. The low-temperature sealing glass paste according to anembodiment of the present invention contains the lead-free low-meltingglass composition according to the embodiment of the present inventionin the form of particles, low-thermal-expansion ceramic particles, and asolvent. The glass frit may fail to achieve good sealing and/or bonding,if containing the lead-free low-melting glass composition according tothe embodiment of the present invention in the content less than 40volume percent, or if containing the low-thermal-expansion ceramicparticles in the content greater than 60 volume percent.

Some low-thermal-expansion ceramic particles allow the lead-freelow-melting glass composition according to the embodiment of the presentinvention to less undergo crystallization. The glass frit or glass pastemay preferably contain, as such low-thermal-expansion ceramic particles,at least one selected from the group consisting of zirconium phosphatetungstate (Zr₂(WO₄) (PO₄)₂) quartz glass (SiO₂), zirconium silicate(ZrSiO₄), aluminum oxide (Al₂O₃), mullite (3Al₂O₃.2SiO₂), and niobiumoxide (Nb₂O₅). Among these low-thermal-expansion ceramic particles,zirconium phosphate tungstate (Zr₂(WO₄) (PO₄)₂) and/or a compoundcontaining mainly zirconium phosphate tungstate (Zr₂(WO₄) (PO₄)₂) iseffective to allow the low-temperature sealing glass frit according tothe embodiment of the present invention to less undergo thermalexpansion. The glass frit preferably contains at least one of thecomponents in a content of 30 to 50 volume percent. Some solvents allowthe lead-free low-melting glass composition according to the embodimentof the present invention to less undergo crystallization. Such solventsare exemplified by α-terpineol and diethylene glycol n-butyl etheracetate, of which α-terpineol is particularly effective. Thelow-temperature sealing glass paste may further contain one or moreadditives such as viscosity modifier and wetting agents as needed so asto control the stability and coatability.

Assume that the low-temperature sealing glass frit or low-temperaturesealing glass paste according to the embodiment of the present inventionis used for sealing and/or bonding to form a glass-sealed component. Inthis case, the low-temperature sealing glass frit or low-temperaturesealing glass paste is arranged in or applied to a portion of an articleto be sealed or to be bonded, and is fired at a temperature higher thanthe softening point T_(s) of the contained lead-free low-melting glasscomposition by about 20° C. to about 60° C. The low-temperature sealingglass frit and low-temperature sealing glass paste according to theembodiments of the present invention each contain the lead-freelow-melting glass composition having a lower softening point and havinga smaller crystallization tendency, can thereby soften and flow moresatisfactorily at a low temperature, and can be fired at a lowertemperature. This reduces the burden on the environment and still allowsthe glass-sealed component to less undergo thermal damage (to havehigher functions) and to offer better productivity (with reduced takttime). In addition, the lead-free low-melting glass compositionaccording to the embodiment of the present invention has good chemicalstability. This allows the glass-sealed component to have reliability atcertain level.

(Conductive Material and Conductive Glass Paste)

The conductive material according to an embodiment of the presentinvention contains 5 to 100 volume percent of the lead-free low-meltingglass composition according to the embodiment of the present invention,and 0 to 95 volume percent of metal particles. The conductive glasspaste according to the embodiment of the present invention contains thelead-free low-melting glass composition according to the embodiment ofthe present invention in the form of particles, metal particles, and asolvent. The conductive material, if containing the lead-freelow-melting glass composition according to the embodiment of the presentinvention in a content less than 5 volume percent, or if containing themetal particles in a content greater than 95 volume percent, may causeinsufficient sintering between the metal particles or may offerinsufficient bonding (adhesion) to a substrate.

Some metal particles offer good conductivity when mixed with thelead-free low-melting glass composition according to the embodiment ofthe present invention. Such metal particles may include at least oneselected from the group consisting of silver (Ag), silver alloys, copper(Cu), copper alloys, aluminum (Al), aluminum alloys, tin (Sn), and tinalloys. Of these metal particles, silver (Ag) and/or aluminum (Al)particles are effective for allowing the conductive material accordingto the embodiment of the present invention to have a lower electricresistance. The conductive material may contain at least one of silver(Ag) and aluminum (Al) preferably in the content of 10 to 90 volumepercent. This is because the lead-free low-melting glass compositionaccording to the embodiment of the present invention can accelerate thesintering of silver (Ag) particles and can remove the surface oxide filmof aluminum (Al) particles. Alpha-terpineol and diethylene glycoln-butyl ether acetate (e.g., Butyl CARBITOL Acetate) are preferred asthe solvent for the lead-free low-melting glass composition according tothe embodiment of the present invention, of which α-terpineol isparticularly effective, as with the low-temperature sealing glass pasteaccording to the embodiment of the present invention. The conductiveglass paste may further contain one or more additives such as viscositymodifiers and wetting agents as needed so as to control the stabilityand coatability.

Assume that the conductive material or conductive glass paste accordingto the embodiment of the present invention is used so as to form anelectrode/interconnection and/or a conductive junction in anelectrical/electronic component. In this case, the conductive materialor conductive glass paste may be arranged in or applied to apredetermined portion typically of a substrate, and is fired at atemperature higher than the softening point T_(s) of the containedlead-free low-melting glass composition by about 20° C. to about 60° C.Assume that the metal particles to be used include a metal that issusceptible to oxidation. In this case, the firing is preferablyperformed in an inert gas atmosphere or in a vacuum atmosphere so as toprevent the metal particles from oxidation.

The conductive material and conductive glass paste according toembodiments of the present invention contain the lead-free low-meltingglass composition having a lower softening point and a smallercrystallization tendency, can thereby soften and flow moresatisfactorily at a low temperature, and can be fired at a lowertemperature. Specifically, the conductive material and conductive glasspaste can form the electrode/interconnection and/or the conductivejunction at a lower temperature, namely, can be fired at a lowertemperature. This reduces the burden on the environment and still allowsthe electrical/electronic component to undergo less thermal damage (tohave higher functions) and to offer better productivity (with reducedtakt time). In addition, the lead-free low-melting glass compositionaccording to the embodiment of the present invention has good chemicalstability. This allows the electrical/electronic component to havereliability at a certain level.

(Glass-Sealed Component)

The glass-sealed component according to an embodiment of the presentinvention is not limited, as long as including a portion sealed and/orbonded with any of the low-temperature sealing glass frit andlow-temperature sealing glass paste according to the embodiments of thepresent invention. Preferred examples of the glass-sealed componentinclude vacuum-insulating double glass panels applied typically towindow panes; as well as display panels such as plasma display panels,organic electroluminescent display panels, and fluorescent displaytubes. The glass frit and glass paste can also be expanded typicallyinto bonding in electrical/electronic components such as quartzresonators, IC ceramic packages, and semiconductor sensors.

(Electrical/Electronic Component)

The electrical/electronic component according to an embodiment of thepresent invention is not limited, as long as including anelectrode/interconnection and/or a conductive junction formed using anyof the conductive material and conductive glass paste according toembodiments of the present invention. Preferred examples of theelectrical/electronic component include solar cells, image displaydevices, multilayer capacitors, quartz resonators, LEDs, andmultilayered circuit boards.

EXAMPLES

The present invention will be illustrated in further detail withreference to specific experimental examples. It should be noted,however, that the experimental examples are never construed to limit thescope of the present invention; and that various modifications andvariations are possible without deviating from the spirit and scope ofthe present invention.

Experimental Example 1

In this experimental example, a trace amount of any of yttrium oxide andlanthanoid oxides was added as an additional component to a lead-freelow-melting glass composition containing a vanadium oxide, a telluriumoxide, and a silver oxide as principal components. In this process, howthe addition affects the glass properties was examined. The lead-freelow-melting glass composition basically contains21V₂O₅-38TeO₂-37Ag₂O-3BaO-1WO₃ (mole percent) as a formulation uponglass production. The yttrium oxide used herein was Y₂O₃, and thelanthanoid oxides were La₂O₃, CeO₂, Pr₂O₃, Nd₂O₃, Sm₂O₃, Gd₂O₃, Dy₂O₃,Er₂O₃, and Yb₂O₃. The lead-free low-melting glass composition containedany one of these oxides in a content of 0.3 mole percent. The additionalcomponent was added while replacing part of WO₃. Namely, the WO₃ contentherein was set to 0.7 mole percent.

In this experimental example, eleven different lead-free low-meltingglass compositions VTA-00 to VTA-10 including one having the basicformulation were prepared. The resulting lead-free low-melting glasscompositions were examined and evaluated on vitrification,characteristic temperatures in relation to crystallization tendency, andchemical stability. VTA-00 had the basic glass formulation of21V₂O₅-38TeO₂-37Ag₂O-3BaO-1WO₃ (mole percent). VTA-01 to VTA-10 areglass compositions containing WO₃ in the content of 0.7 mole percent andrespectively containing Y₂O₃, La₂O₃, CeO₂, Pr₂O₃, Nd₂O₃, Sm₂O₃, Gd₂O₃,Dy₂O₃, Er₂O₃, and Yb₂O₃ in the content of 0.3 mole percent.

(Preparation of Lead-Free Low-Melting Glass Composition)

Lead-free low-melting glass compositions VTA-00 to VTA-10 as in Table 1were prepared. The formulations given in Table 1 are formulations uponglass production. Starting materials used herein were powders of V₂O₅(Shinko Chemical Co., Ltd.), TeO₂ (Kojundo Chemical Laboratory Co.,Ltd.), Ag₂O (Wako Pure Chemical Industries, Ltd.), BaCO₃ (KojundoChemical Laboratory Co., Ltd.), and WO₃ (Kojundo Chemical LaboratoryCo., Ltd.). The yttrium oxide and lanthanoid oxides used herein werepowders of Y₂O₃, La₂O₃, CeO₂, Pr₂O₃, Nd₂O₃, Sm₂O₃, Gd₂O₃, Dy₂O₃, Er₂O₃,and Yb₂O₃ each supplied by Kojundo Chemical Laboratory Co., Ltd.

Individual starting material powders were weighed, formulated, and mixedto a total amount of about 200 g, and the mixture was placed in a quartzglass crucible. The quartz glass crucible housing the starting materialpowder mixture was placed in a glass melter, heated to a temperature of700° C. to 750° C. at a rate of temperature rise of about 10° C. perminute, and held at the temperature for one hour with stirring using analuminum oxide rod so as to uniformize the formulation of the melt inthe quartz glass crucible. The quartz glass crucible was retrieved fromthe glass melter, the melt was poured into a stainless steel moldpreviously heated to about 120° C., and thereby yielded the lead-freelow-melting glass compositions VTA-00 to VTA-10. Next, each of theprepared lead-free low-melting glass compositions was pulverized to asize of about 10 μm.

TABLE 1 Vitrification, characteristic temperatures, crystallizationtendency, and chemical stability of lead-free low-melting glasscompositions Additional Characteristic temperatures (° C.) componentGlass Yield Softening Crystallization (0.3 mole transition point pointonset temperature Glass number percent) Vitrification Point Tg Mg TsTcry Comparative Basic formulation¹⁾ VTA-00 None Accepted 167 182 216260 Example Example Yttrium oxide²⁾ VTA-01 Y₂O₃ Accepted 165 183 219 Noexothermic crystallization peak Lanthanoid VTA-02 La₂O₃ Accepted 165 186217 No exothermic oxide²⁾ crystallization peak VTA-03 CeO₂ Accepted 167181 216 320 VTA-04 Pr₂O₃ Accepted 168 186 222 260 VTA-05 Nd₂O₃ Accepted165 183 220 260 VTA-06 Sm₂O₃ Accepted 164 181 217 260 VTA-07 Gd₂O₃Accepted 168 183 219 260 VTA-08 Dy₂O₃ Accepted 165 182 217 260 VTA-09Er₂O₃ Accepted 166 182 218 295 VTA-10 Yb₂O₃ Accepted 167 184 219 275Comparative Conventional lead- PB-01 None Accepted 313 332 386 — Examplecontaining glass³⁾ Amount of heat Chemical stability liberated byReduction of Water Acid crystallization crystallization resistanceresistance Glass number (μV) tendency test test Comparative Basicformulation¹⁾ VTA-00 12 — Accepted Accepted Example Example Yttriumoxide²⁾ VTA-01 0 5 Accepted Accepted Lanthanoid VTA-02 0 5 AcceptedAccepted oxide²⁾ VTA-03 4 4 Accepted Accepted VTA-04 3 3 AcceptedAccepted VTA-05 3 3 Accepted Accepted VTA-06 3 3 Accepted AcceptedVTA-07 5 3 Accepted Accepted VTA-08 3 3 Accepted Accepted VTA-09 0.8 4Accepted Accepted VTA-10 0.5 4 Accepted Accepted ComparativeConventional lead- PB-01 — — Rejected Rejected Example containingglass³⁾ ¹⁾21V₂O₅—38TeO₂—38Ag₂O—3BaO—1WO₃ (mole percent)²⁾21V₂O₅—38TeO₂—38Ag₂O—3BaO—0.7WO₃—0.3 additional component (molepercent) ³⁾84PbO—13B₂O₃—2SiO₂—1Al₂O₃ (mass percent)

(Evaluation of Vitrification)

The prepared lead-free low-melting glass compositions VTA-00 to VTA-10were subjected to X-ray diffractometry to determine whethercrystallization occurred in each glass composition in the form of powderand to evaluate the vitrification. A sample suffering from nocrystallization was considered to be vitrified satisfactorily andevaluated as “accepted”. In contrast, a sample suffering fromcrystallization was considered to fail to have a homogeneous amorphousstate as a result of vitrification and evaluated as “rejected”.

(Evaluation of Characteristic Temperatures and Crystallization Tendency)

The prepared lead-free low-melting glass compositions VTA-00 to VTA-10were subjected to differential thermal analysis (DTA) using a powder ofeach glass composition to evaluate or determine their characteristictemperatures and crystallization tendency. The DTA was performed with amacrocell system, where about 500 mg of a sample glass powder was placedin the macrocell, heated in the air from room temperature up to 400° C.at a rate of temperature rise of 5° C. per minute to plot a DTA curve asillustrated in FIG. 1. Based on the plotted DTA curve, the glasstransition point T_(g), yield point M_(g), softening point T_(s), andcrystallization onset temperature T_(cry) were determined. In addition,the size of the exothermic crystallization peak was measured todetermine the amount of heat liberated by crystallization. How thecrystallization tendency was effectively reduced was evaluated in fivegrades based on the crystallization onset temperature T_(cry) and theamount of heat liberated by crystallization. A sample offering noexothermic crystallization peak as compared with the VTA-00 glass havingthe basic formulation was evaluated as extremely good and rated “5”. Asample offering both a higher crystallization onset temperature T_(cry)and a smaller amount of liberated heat was evaluated as very good andrated “4”, and a sample offering one of the two factors was evaluated asgood and rated “3”. In contrast, a sample offering both a lowercrystallization onset temperature T_(cry) and a larger amount ofliberated heat was evaluated as very faulty and rated “1”, and a sampleoffering one of the two factors was evaluated as faulty and rated “2”.Samples having a rating “3” or greater were regarded as having aneffectively reduced crystallization tendency.

(Evaluation of Chemical Stability)

The prepared lead-free low-melting glass compositions VTA-00 to VTA-10were each subjected to a water resistance test and an acid resistancetest to evaluate a chemical stability. Glass test specimens were cullethaving a size of about 10 to about 20 mm before pulverization. In thewater resistance test, the cullet was immersed in pure water at 50° C.for 48 hours. In the acid resistance test, the cullet was immersed in a1 N aqueous nitric acid solution at room temperature for 24 hours. Thecullet specimens after the two tests were visually observed onappearance. A sample offering no change in appearance was evaluated as“accepted”, whereas a sample offering a change in appearance wasevaluated as “rejected”. As a comparative example, cullet ofconventional lead-containing low-melting glass composition PB-1 wassubjected to the tests as above. The lead-containing low-melting glasscomposition used as a comparative example had a formulation of84PbO-13B₂O₃-2SiO₂-1Al₂O₃ (mass percent), a glass transition point T_(g)of 313° C., a yield point M_(g) of 332° C., and a softening point T_(s)of 386° C.

Table 1 shows the evaluation results of the vitrification,characteristic temperatures in relation to crystallization tendency, andchemical stability of the lead-free low-melting glass compositionsVTA-00 to VTA-10. Table 1 also shows the evaluation results of theconventional lead-containing low-melting glass composition PB-01.

The lead-free low-melting glass composition VTA-00 (comparative example)having the basic formulation had significantly low characteristictemperatures T_(g), M_(g), and T_(s) and can soften and flow at asignificantly low temperature as compared with the lead-containinglow-melting glass composition PB-01 (comparative example). The sampleVTA-00 had very high chemical stability in spite of having lowcharacteristic temperatures. The sample, however, had a crystallizationtendency at a temperature around 260° C. The sample had a differencebetween the temperatures T_(cry) and T_(s) of about 40° C., but offereda relatively large amount of heat liberated by crystallization, andcould less satisfactorily soften and flow upon heating-firing. It wasdifficult to expand the sample into the sealing and/or bonding and intothe formation of electrodes/interconnections and conductive junctions.In contrast, the lead-free low-melting glass compositions VTA-01 toVTA-10 (examples) containing a trace amount of one of yttrium oxide andlanthanoid oxides had a still lower crystallization tendency as comparedwith the comparative example VTA-00. In addition, the examples VTA-01 toVTA-10 had little rise in the characteristic temperatures T_(g), M_(g),and T_(s) and suffered from approximately no deterioration in chemicalstability. For lanthanoid oxides, not all the lanthanoid elements of theperiodic table were investigated herein. The lanthanoid elements,however, are known to have similar properties to each other due to theirelectronic states. Obviously, all the lanthanoid oxides can offereffects as mentioned above.

In particular, the data of VTA-01 to VTA-03, VTA-09, and VTA-10demonstrated that the presence of at least one of Y₂O₃, La₂O₃, CeO₂,Er₂O₃, and Yb₂O₃ significantly effectively contributes to a lowercrystallization tendency. The data also demonstrated that, of thelanthanoid elements in lanthanoid oxides, those positioned at both endsof the range of atomic numbers (57 to 71) in the periodic table moreeffectively offer a lower crystallization tendency as compared withlanthanoid elements positioned in the center part in the range. Thepresence of Y₂O₃ and La₂O₃ most effectively contributes to a lowercrystallization tendency. The samples VTA-01 and VTA-02 respectivelycontaining Y₂O₃ and La₂O₃ could have such a significantly lowcrystallization tendency as to offer no exothermic crystallization peak.

These data and considerations demonstrated as follows. Assume thatlead-free low-melting glass compositions contain a vanadium oxide, atellurium oxide, and a silver oxide as principal components. Theselead-free low-melting glass compositions, when further containing atleast one of yttrium oxide and lanthanoid oxides as an additionalcomponent, can particularly have a lower crystallization tendencywithout significant rise in the softening point T_(s) and withoutdeterioration in chemical stability. In particular, the presence of anyof Y₂O₃, La₂O₃, CeO₂, Er₂O₃ and Yb₂O₃ effectively offer a lowercrystallization tendency, of which the presence of Y₂O₃ and/or La₂O₃ ismost effective.

Experimental Example 2

In this experimental example, lead-free low-melting glass compositionscontaining a vanadium oxide, a tellurium oxide, and a silver oxide asprincipal components and further containing any of yttrium oxide andlanthanoid oxides were prepared. How the content of any of the yttriumoxide and lanthanoid oxides affects the vitrification, characteristictemperatures in relation to crystallization tendency, and chemicalstability was investigated. The yttrium oxide used herein was Y₂O₃, andthe lanthanoid oxides used herein were La₂O₃, CeO₂, and Er₂O₃, each ofwhich was contained in a content of 0 to 5 mole percent.

The investigated formulations (mole percent) of the lead-freelow-melting glass compositions are given in Table 2. The lead-freelow-melting glass compositions were examined to evaluate thevitrification, characteristic temperatures in relation tocrystallization tendency, and chemical stability, and the results aregiven in Table 3. The lead-free low-melting glass compositions wereprepared and evaluated by the procedure of Experimental Example 1.VTA-11, VTA-26, VTA-27, VTA-45, VTA-46, and VTA-56 in Tables 2 and 3 arelead-free low-melting glass compositions containing none of yttriumoxide and lanthanoid oxides and were used as comparative examples. Othersamples are lead-free low-melting glass compositions containing Y₂O₃(VTA-12 to VTA-25), La₂O₃ (VTA-28 to VTA-44), CeO₂ (VTA-47 to VTA-55),or Er₂O₃ (VTA-57 to VTA-63).

TABLE 2 Formulation (mole percent) of lead-free low-melting glasscomposition Principal Secondary Additional Glass component componentcomponent number V₂O₅ TeO₂ Ag₂O BaO WO₃ P₂O₅ Y₂O₃ La₂O₃ CeO₂ Er₂O₃VTA-11 20.0 40.0 40.0 — — — 0.0 — — — Comparative Example VTA-12 20.040.0 39.9 — — — 0.1 — — — VTA-13 20.0 38.0 36.0 5.0 0.7 — 0.3 — — —VTA-14 20.0 40.0 39.5 — — — 0.5 — — — VTA-15 20.0 35.0 40.0 2.0 1.0 2.00.5 — — — VTA-16 20.0 36.5 30.0 5.0 5.0 3.0 0.5 — — — VTA-17 20.0 40.026.5 13.0  — — 0.5 — — — VTA-18 20.0 36.5 30.0 3.0 7.0 3.0 0.5 — — —VTA-19 20.0 40.0 39.0 — — — 1.0 — — — VTA-20 20.0 40.0 36.0 1.0 1.0 1.01.0 — — — VTA-21 20.0 40.0 39.0 — — — 0.5 0.5 — — VTA-22 20.0 40.0 38.0— — — 2.0 — — — VTA-23 20.0 40.0 38.0 — — — 1.0 1.0 — — VTA-24 20.0 39.038.0 — — — 3.0 — — — VTA-25 20.0 39.0 36.0 — — — 5.0 — — — VTA-26 20.037.0 33.0 5.0 5.0 — — 0.0 — — Comparative Example VTA-27 20.0 40.0 30.05.0 5.0 — — 0.0 — — Comparative Example VTA-28 20.0 39.9 30.0 5.0 5.0 —— 0.1 — — VTA-29 20.0 38.0 36.0 5.0 0.7 — — 0.3 — — VTA-30 20.0 39.530.0 5.0 5.0 — — 0.5 — — VTA-31 20.0 37.5 35.0 5.0 2.0 — — 0.5 — —VTA-32 20.0 36.5 33.0 5.0 5.0 — — 0.5 — — VTA-33 20.0 37.5 35.0 5.0 —2.0 — 0.5 — — VTA-34 27.0 35.0 27.0 — 4.0 6.5 — 0.5 — — VTA-35 19.0 37.533.0 4.0 4.0 2.0 — 0.5 — — VTA-36 20.0 36.0 32.0 6.0 5.0 — — 1.0 — —VTA-37 20.0 38.0 28.0 5.0 8.0 — — 1.0 — — VTA-38 25.5 35.0 25.5 — 8.05.0 — 1.0 — — VTA-39 20.0 40.0 29.0 5.0 5.0 — 0.5 0.5 — — VTA-40 20.036.0 33.0 5.0 5.0 — 0.5 0.5 — — VTA-41 20.0 37.0 31.0 5.0 5.0 — — 2.0 —— VTA-42 17.0 34.0 34.0 6.0 5.0 2.0 1.0 1.0 — — VTA-43 20.0 37.0 30.05.0 5.0 — — 3.0 — — VTA-44 20.0 37.0 28.0 5.0 5.0 — — 5.0 — — VTA-4520.0 39.0 36.0 5.0 0.0 — Comparative Example VTA-46 20.0 39.0 36.0 5.00.0 — Comparative Example VTA-47 20.0 38.9 36.0 5.0 0.1 — VTA-48 20.038.5 36.0 5.0 0.5 — VTA-49 20.0 38.5 36.0 5.0 0.5 — VTA-50 20.0 38.535.5 5.0 1.0 — VTA-51 20.0 38.5 35.5 5.0 1.0 — VTA-52 20.0 38.5 35.5 5.00.3 0.3 0.4 — VTA-53 20.0 38.0 35.0 5.0 2.0 — VTA-54 20.0 37.0 35.0 5.03.0 — VTA-55 20.0 35.0 35.0 5.0 5.0 — VTA-56 30.0 30.0 30.0 5.0 — 5.0 —— — 0.0 Comparative Example VTA-57 30.0 30.0 30.0 5   — 4.9 — — — 0.1VTA-58 30.0 30.0 30.0 5   — 4.5 — — — 0.5 VTA-59 30.0 30.0 30.0 4.7 —4.5 — 0.3 — 0.5 VTA-60 30.0 30.0 30.0 4.5 — 4.5 — — — 1.0 VTA-61 30.030.0 30.0 4.0 — 4.0 — — — 2.0 VTA-62 30.0 30.0 30.0 3.5 — 3.5 — — — 3.0VTA-63 30.0 30.0 30.0 2.5 — 2.5 — — — 5.0

TABLE 3 Vitrification, characteristic temperatures, crystallizationtendency, and chemical stability of lead-free low-melting glasscompositions Amount Characteristic temperatures (° C.) of heat Chemicalstability Glass Yield Softening Crystallization liberated by Reductionof Water Acid Glass transition point point onset temperaturecrystallization crystallization resistance resistance numberVitrification Point Tg Mg Ts Tcry (μV) tendency test test VTA-11Accepted 153 168 196 260 150 — Accepted Accepted Comparative ExampleVTA-12 Accepted 151 169 198 290 25 4 Accepted Accepted VTA-13 Accepted169 186 222 No exothermic peak 0 5 Accepted Accepted VTA-14 Accepted 154170 202 295 2 4 Accepted Accepted VTA-15 Accepted 185 203 236 343 1 4Accepted Accepted VTA-16 Accepted 220 244 280 No exothermic peak 0 5Accepted Accepted VTA-17 Accepted 210 243 279 No exothermic peak 0 5Accepted Accepted VTA-18 Accepted 221 241 278 No exothermic peak 0 5Accepted Accepted VTA-19 Accepted 158 175 211 281 7 4 Accepted AcceptedVTA-20 Accepted 175 192 224 315 2 4 Accepted Accepted VTA-21 Accepted158 178 209 284 8 4 Accepted Accepted VTA-22 Accepted 157 180 215 275 194 Accepted Accepted VTA-23 Accepted 156 179 212 285 15 4 AcceptedAccepted VTA-24 Accepted 160 172 208 261 41 3 Accepted Accepted VTA-25Accepted 168 185 224 246 55 2 Accepted Accepted VTA-26 Accepted 186 203236 285 26 — Accepted Accepted Comparative Example VTA-27 Accepted 191208 242 305 14 — Accepted Accepted Comparative Example VTA-28 Accepted189 207 240 335 1 4 Accepted Accepted VTA-29 Accepted 168 189 220 Noexothermic peak 0 5 Accepted Accepted VTA-30 Accepted 195 212 251 Noexothermic peak 0 5 Accepted Accepted VTA-31 Accepted 174 196 231 Noexothermic peak 0 5 Accepted Accepted VTA-32 Accepted 184 203 239 Noexothermic peak 0 5 Accepted Accepted VTA-33 Accepted 176 202 240 Noexothermic peak 0 5 Accepted Accepted VTA-34 Accepted 220 236 274 Noexothermic peak 0 5 Accepted Accepted VTA-35 Accepted 197 214 260 Noexothermic peak 0 5 Accepted Accepted VTA-36 Accepted 190 212 247 Noexothermic peak 0 5 Accepted Accepted VTA-37 Accepted 223 240 280 Noexothermic peak 0 5 Accepted Accepted VTA-38 Accepted 225 243 280 Noexothermic peak 0 5 Accepted Accepted VTA-39 Accepted 194 215 250 Noexothermic peak 0 5 Accepted Accepted VTA-40 Accepted 187 207 245 Noexothermic peak 0 5 Accepted Accepted VTA-41 Accepted 194 209 253 3770.5 4 Accepted Accepted VTA-42 Accepted 219 238 280 400 0.3 4 AcceptedAccepted VTA-43 Accepted 198 213 251 310 2 3 Accepted Accepted VTA-44Accepted 204 223 262 290 7 2 Accepted Accepted VTA-45 Accepted 187 180218 258 33 — Accepted Accepted Comparative Example VTA-46 Accepted 175184 225 283 12 — Accepted Accepted Comparative Example VTA-47 Accepted167 179 218 290 3 4 Accepted Accepted VTA-48 Accepted 169 185 221 2830.5 4 Accepted Accepted VTA-49 Accepted 176 191 226 306 7 4 AcceptedAccepted VTA-50 Accepted 170 188 225 316 0.2 4 Accepted Accepted VTA-51Accepted 173 190 230 345 0.3 4 Accepted Accepted VTA-52 Accepted 169 192227 No exothermic peak 0 5 Accepted Accepted VTA-53 Accepted 176 197 236273 4 4 Accepted Accepted VTA-54 Accepted 172 200 235 260 8 3 AcceptedAccepted VTA-55 Accepted 168 198 233 246 17 2 Accepted Accepted VTA-56Accepted 224 247 284 337 5 — Accepted Accepted Comparative ExampleVTA-57 Accepted 222 245 280 367 0.9 4 Accepted Accepted VTA-58 Accepted225 244 277 No exothermic peak 0 5 Accepted Accepted VTA-59 Accepted 227246 280 No exothermic peak 0 5 Accepted Accepted VTA-60 Accepted 224 245275 No exothermic peak 0 5 Accepted Accepted VTA-61 Accepted 226 245 274358 2 4 Accepted Accepted VTA-62 Accepted 218 241 268 336 3 3 AcceptedAccepted VTA-63 Accepted 209 230 258 310 11 1 Accepted Accepted

VTA-12 to VTA-25 were compared with VTA-11. The comparison demonstratedthat VTA-12 to VTA-24 containing yttrium oxide Y₂O₃ in a content of 0.1to 3.0 mole percent had a lower crystallization tendency. VTA-21 andVTA-23 further contained a lanthanoid oxide La₂O₃ in addition to Y₂O₃.VTA-13, VTA-15 to VTA-18, and VTA-20 contained at least one secondarycomponent selected from BaO, WO₃, and P₂O₅. The presence of at least oneselected from BaO, WO₃, and P₂O₅ in addition to Y₂O₃ (and further La₂O₃)had a still lower crystallization tendency. VTA-25 containing 5 molepercent of Y₂O₃ had a lower amount of heat liberated by crystallizationabout one third that of VTA-11, but had a lower crystallization onsettemperature T_(cry). Of VTA-12 to VTA-24, VTA-12 to VTA-23 particularlyeffectively had a lower crystallization tendency and had a total contentof Y₂O₃ and La₂O₃ of 0.1 to 2.0 mole percent. VTA-12 to VTA-25 hadchemical stability without deterioration as compared with VTA-11 andeach had a glass softening point T_(s) of 280° C. or lower. Thesoftening point T_(s), crystallization onset temperature T_(cry), andamount of heat liberated by crystallization of these samples weresynthetically evaluated. This demonstrated that glass composition havinga total content of Y₂O₃ and La₂O₃ of 0.1 to 1.0 mole percent are mosteffective, as indicated in data of VTA-12 to VTA-21.

VTA-28 to VTA-44 were compared with VTA-26 and VTA-27. The comparisondemonstrated that VTA-28 to VTA-43 containing 0.1 to 3.0 mole percent oflanthanoid oxide La₂O₃ had a lower crystallization tendency. VTA-39,VTA-40, and VTA-42 further contained yttrium oxide Y₂O₃ in addition toLa₂O₃. In particular, VTA-29 to VTA-40 could have such a significantlylower crystallization tendency as to offer no exothermic crystallizationpeak. This is because these samples contained at least one of BaO, WO₃,and P₂O₅ in addition to La₂O₃ (and further Y₂O₃) as demonstrated by acomparison of VTA-26 and VTA-27 with VTA-11. As compared with VTA-27,VTA-44 containing 5 mole percent of La₂O₃ could have an amount of heatliberated by crystallization as reduced to the half, but had a somewhatlower crystallization onset temperature T_(cry). Of VTA-28 to VTA-43,VTA-28 to VTA-42 having a total content of La₂O₃ and Y₂O₃ of 0.1 to 2.0mole percent had a particularly effectively lowered crystallizationtendency. As compared with VTA-26 and VTA-27, VTA-28 to VTA-44 offeredno deterioration in chemical stability and each had a glass softeningpoint T_(s) of 280° C. or lower. The softening point T_(s),crystallization onset temperature T_(cry), and amount of heat liberatedby crystallization of the samples were synthetically evaluated. Thisdemonstrated that glass compositions having a total content of La₂O₃ andY₂O₃ of 0.1 to 1.0 mole percent are most effective as indicated in dataof VTA-28 to VTA-40.

VTA-47 to VTA-55 were compared with VTA-45 and VTA-46. This demonstratedthat VTA-47 to VTA-54 containing 0.1 to 3.0 mole percent of a lanthanoidoxide CeO₂ could have a lower crystallization tendency. VTA-47 to VTA-54further contained a secondary component selected from BaO, WO₃, and P₂O₅in addition to CeO₂. VTA-52 further contained Y₂O₃ and La₂O₃ in additionto CeO₂. VTA-52 could have such a significantly lower crystallizationtendency as to offer no exothermic crystallization peak as compared withVTA-50 containing CeO₂ alone as the additional component. As comparedwith VTA-45, VTA-55 containing 5 mole percent of CeO₂ could have anamount of heat liberated by crystallization as reduced to the half, buthad a somewhat lower crystallization onset temperature T_(cry). OfVTA-47 to VTA-54, VTA-47 to VTA-53 having a total content of CeO₂, Y₂O₃,and La₂O₃ of 0.1 to 2.0 mole percent could effectively have a lowercrystallization tendency. As compared with VTA-45 and VTA-46, VTA-47 toVTA-55 offered no deterioration in chemical stability and had a glasssoftening point T_(s) of 280° C. or lower. The softening point T_(s),crystallization onset temperature T_(cry), and amount of heat liberatedby crystallization of the samples were synthetically evaluated. Thisdemonstrated that glass compositions having a total content of CeO₂,Y₂O₃, and La₂O₃ of 0.1 to 1.0 mole percent were most effective, asindicated in data of VTA-47 to VTA-52.

Of VTA-56 to VTA-63, VTA-57 to VTA-62 containing 0.1 to 3.0 mole percentof a lanthanoid oxide Er₂O₃ could have a lower crystallization tendencyas compared with VTA-56. VTA-57 to VTA-62 further contained BaO and P₂O₅as secondary components in addition to Er₂O₃. VTA-59 further containedanother lanthanoid oxide La₂O₃ in addition to Er₂O₃. In particular,VTA-58 to VTA-60 could have such a significantly lower crystallizationtendency as to offer no exothermic crystallization peak. This is becausethe samples contained BaO and P₂O₅ as secondary components in additionto Er₂O₃ (and further La₂O₃) as demonstrated by the comparison betweenVTA-56 and VTA-11. VTA-63 containing 5 mole percent of Er₂O₃ sufferedfrom both a lower crystallization onset temperature T_(cry) and a largeramount of heat liberated by crystallization and had a highercrystallization tendency contrarily, as compared with VTA-56 containingno Er₂O₃. Of VTA-57 to VTA-62, VTA-57 to VTA-61 having a total contentof Er₂O₃ and La₂O₃ of 0.1 to 2.0 mole percent could effectively have alower crystallization tendency. VTA-57 to VTA-63 offered nodeterioration in chemical stability as compared with VTA-56 and had aglass softening point T_(s) of 280° C. or lower. The softening pointT_(s), crystallization onset temperature T_(cry), and amount of heatliberated by crystallization of the samples were syntheticallyevaluated. This demonstrated that glass compositions having a totalcontent of Er₂O₃ and La₂O₃ of 0.1 to 1.0 mole percent were mosteffective, as indicated in data of VTA-57 to VTA-60.

These data and considerations demonstrated as follows. Assume thatlead-free low-melting glass compositions contain a vanadium oxide, atellurium oxide, and a silver oxide as principal components. Theselead-free low-melting glass compositions, when further containing atleast one selected from yttrium oxide and lanthanoid oxides in thecontent of 0.1 to 3.0 mole percent, can effectively have a lowercrystallization tendency. The content of at least one selected fromyttrium oxide and lanthanoid oxides is more preferably 0.1 to 2.0 molepercent, and is most effectively and preferably 0.1 to 1.0 mole percentwhen the softening point T_(s), crystallization onset temperatureT_(cry), and amount of heat liberated by crystallization of the samplesare synthetically evaluated. In addition, the glass compositions, whenfurther containing at least one selected from BaO, WO₃, and P₂O₅ as asecondary component, can more effectively have a still lowercrystallization tendency.

Obviously, lead-free low-melting glass compositions, when furthercontaining at least one selected from yttrium oxide and lanthanoidoxides, can have a lower crystallization tendency regardless of theirglass formulations, as long as containing a vanadium oxide, a telluriumoxide, and a silver oxide as principal components. However, there can bepreferred content ranges (formulation ranges) on the principalcomponents of V₂O₅, TeO₂, and Ag₂O and on the secondary components ofBaO, WO₃, and P₂O₅, in order to expand the glass compositions into thesealing and/or bonding of glass-sealed components andelectrical/electronic components and into the formation ofelectrodes/interconnections and conductive junctions. For the principalcomponents, Tables 2 and 3 demonstrated that the total content of V₂O₅,TeO₂, and Ag₂O are effectively 85 mole percent or more, and the contentsof TeO₂ and Ag₂O are each effectively 1 to 2 times as much as thecontent of V₂O₅. For the secondary component, Tables 2 and 3 alsodemonstrated that the glass compositions effectively contain at leastone selected from BaO, WO₃, and P₂O₅ in a content of 13 mole percent orless. The glass compositions, as having the configuration, can act aslead-free low-melting glass compositions having a softening point T_(s)of 280° C. or lower. In addition, the glass compositions, as furthercontaining at least one selected from yttrium oxide and lanthanoidoxides, can have a crystallization onset temperature T_(cry) higher thanthe softening point T_(s) by 60° C. or more and can satisfactorilysoften and flow at a lower temperature as compared with conventionalglass compositions.

Experimental Example 3

In this experimental example, low-temperature sealing glass frits eachcontaining a lead-free low-melting glass composition according to anembodiment of the present invention and low-thermal-expansion ceramicparticles were prepared. Using the frits, a pair of metal substrates, apair of glass substrates, or a pair of ceramic substrates, each of thesame kind, was bonded, and how the pair of substrates was bonded wasevaluated with shear stress. The lead-free low-melting glasscompositions used herein were two different glass compositions VTA-13and VTA-32 (see Tables 2 and 3) in the form of particles. Thelow-thermal-expansion ceramic particles used herein were seven differentparticles of CF-01 to CF-07 (see Table 4). Table 4 also shows thedensity and coefficient of thermal expansion of thelow-thermal-expansion ceramic particles. The lead-free low-melting glasscompositions in Tables 2 and 3 had a density of 5.0 to 6.0 g/cm³ and acoefficient of thermal expansion of 160×10⁻⁷ to 195×10⁻⁷ per degreecentigrade at temperatures in the range of room temperature to 150° C.The metal substrates used herein were aluminum (Al), silver (Ag), copper(Cu), nickel (Ni), and iron (Fe) substrates. The glass substrate was asoda-lime glass substrate, and the ceramic substrate was an aluminumoxide (Al₂O₃) substrate. Each evaluation sample was prepared in thefollowing manner. Initially, a low-temperature sealing glass pastecontaining a lead-free low-melting glass composition in the form ofparticles, low-thermal-expansion ceramic particles, and a solvent wasprepared. The paste was applied to each substrate, dried, andpreliminarily fired. The pair of the substrates was then laminated,heated, and thereby bonded.

TABLE 4 Density and coefficient of thermal expansion of testedlow-thermal-expansion ceramic particles Coefficient of thermalLow-thermal-expansion ceramic Density expansion No. particles (g/cm³)(×10⁻⁷/° C.) CF-01 Zirconium phosphate tungstate 3.8 −32 Zr₂(WO₄) (PO₄)₂CF-02 Zirconium phosphate tungstate 3.8 −30 containing trace amount ofiron tungstate Zr₂(WO₄)(PO₄)₂ containing trace amount of FeWO₄ CF-03Quartz glass 2.2 5 SiO₂ CF-04 Zirconium silicate 4.6 45 ZrSiO₄ CF-05Aluminum oxide 4.0 81 Al₂O₃ CF-06 Mullite 3.2 33 3Al₂O₃•2SiO₂ CF-07Niobium oxide 4.6 12 Nb₂O₅

(Preparation of Low-Temperature Sealing Glass Paste)

A lead-free low-melting glass composition in the form of particles,low-thermal-expansion ceramic particles, and a solvent were blended,mixed, and yielded a series of low-temperature sealing glass pastes. Thelead-free low-melting glass composition particles were VTA-13 and VTA-32in the form of particles having a particle diameter of about 10 μm. Thelow-thermal-expansion ceramic particles were particles of: zirconiumphosphate tungstate (CF-01), zirconium phosphate tungstate containing atrace amount of iron tungstate (CF-02), quartz glass (CF-03), zirconiumsilicate (CF-04), aluminum oxide (CF-05), mullite (CF-06), and niobiumoxide (CF-07), each of which had a particle diameter of about 10 toabout 30 μm. Samples to be heated and fired in an inert gas or vacuumatmosphere contained α-terpineol as the solvent and further containedisobornylcyclohexanol as a viscosity modifier. Samples to be fired inthe air contained diethylene glycol n-butyl ether acetate as the solventand further contained ethyl cellulose as a resin binder. The lead-freelow-melting glass composition particles and the low-thermal-expansionceramic particles were blended in eight different ratios (in volumepercent) of 100:0, 90:10, 80:20, 70:30, 60:40, 50:50, 40:60, and 30:70to give corresponding low-temperature sealing glass pastes. Thelow-temperature sealing glass pastes were prepared so as to have asolids content of about 80 mass percent. The “solids content” refers tothe total content of the lead-free low-melting glass compositionparticles and the low-thermal-expansion ceramic particles.

(Preparation of Evaluation Sample)

FIG. 2 illustrates how to prepare each evaluation sample.

Initially, a cylindrical substrate 1 including a bonding plane 2 andhaving a diameter of 5 mm and a thickness of 5 mm was prepared (step(a)).

Next, the bonding plane 2 of the cylindrical substrate 1 was coated witha low-temperature sealing glass paste 3 by dispensing (step (b)).

The resulting article was dried at 120° C. to 150° C. in the air. Thiswas placed in an electric furnace, heated up to 220° C. at a rate oftemperature rise of 10° C. per minute in an inert gas (nitrogen) or inthe air, held for 15 minutes, heated up to a temperature higher than thesoftening point T_(s) of the contained lead-free low-melting glasscomposition by about 50° C. at the same rate of temperature rise asabove, held for 15 minutes, and thereby formed a low-temperature sealingglass frit 4 on the bonding plane 2 of the cylindrical substrate 1 (step(c)). Specifically, the glass pastes containing the lead-freelow-melting glass compositions VTA-13 and VTA-32 were heatedrespectively up to 270° C. and 290° C.

The resulting article was placed on a plate substrate 5 having athickness of 3 to 5 mm and including a material of the same type withthe cylindrical substrate 1, fastened thereon with a heat-resistantclip, heated up to 270° C. or 290° C. in an inert gas (nitrogen) or inthe air at a rate of temperature rise of 10° C. per minute, held for 15minutes, and yielded a bonded article (step (d)).

The bonded article was subjected to shear stress measurement. Samplesusing a copper (Cu) or iron (Fe) substrate were heated in the inert gas(nitrogen) atmosphere, and samples using the other substrates wereheated in the air. The blending ratio between the lead-free low-meltingglass composition particles and the low-thermal-expansion ceramicparticles in the low-temperature sealing glass paste, and the type ofthe low-thermal-expansion ceramic particles were selected inconsideration of the coefficient of thermal expansion of the substrateto be bonded. The coefficients of thermal expansion of the substratesused are 224×10⁻⁷ per degree centigrade (aluminum (Al)), 197×10⁻⁷ perdegree centigrade (silver (Ag)), 164×10⁻⁷ per degree centigrade (copper(Cu)), 133×10⁻⁷ per degree centigrade (nickel (Ni)), 127×10⁻⁷ per degreecentigrade (iron (Fe)), 88×10⁻⁷ per degree centigrade (soda-lime glass),and 81×10⁻⁷ per degree centigrade (aluminum oxide (Al₂O₃)).

(Evaluation of Bonding)

Each of the bonded articles prepared using the low-temperature sealingglass pastes was examined to measure and evaluate a shear stress. In theshear stress evaluation, the sample having the shear stress of 30 MPa ormore was evaluated as “excellent”, the sample having the shear stress of20 to 30 MPa was evaluated as “good”, the sample having the shear stressof 10 to 20 MPa was evaluated as “moderate”, and the sample having theshear stress of less than 10 MPa was evaluated as “rejected”.

The results of the evaluation of the shear stress in the bonded articlesincluding the different substrates are shown in Tables 5 to 11. Theevaluation results are shown in Table 5 for bonded articles betweenaluminum (Al) substrates; in Table 6 for bonded articles between silver(Ag) substrates; in Table 7 for bonded articles between copper (Cu)substrates; in Table 8 for bonded articles between nickel (Ni)substrates; in Table 9 for bonded articles between iron (Fe) substrates;in Table 10 for bonded articles between soda-lime glass substrates; andin Table 11 for bonded articles between aluminum oxide (Al₂O₃)substrates.

TABLE 5 Evaluated shear stress of bonded articles between aluminumsubstrates Amount (in volume percent) of 100 90 80 lead-free low-meltingglass composition Amount (in volume percent) of 0 10 20low-thermal-expansion ceramic particles VTA-13 CF-04 Excellent ExcellentExcellent CF-05 Excellent Excellent Excellent CF-06 Excellent ExcellentExcellent VTA-32 CF-04 Excellent Excellent Excellent CF-05 ExcellentExcellent Excellent CF-06 Excellent Excellent Excellent

TABLE 6 Evaluated shear stress of bonded articles between silversubstrates Amount (in volume percent) of 100 90 80 lead-free low-meltingglass composition Amount (in volume percent) of 0 10 20low-thermal-expansion ceramic particles VTA-13 CF-04 Excellent ExcellentExcellent CF-05 Excellent Excellent Excellent CF-06 Excellent ExcellentExcellent VTA-32 CF-04 Excellent Excellent Excellent CF-05 ExcellentExcellent Excellent CF-06 Excellent Excellent Excellent

TABLE 7 Evaluated shear stress of bonded articles between coppersubstrates Amount (in volume percent) of 80 70 60 lead-free low-meltingglass composition Amount (in volume percent) of 20 30 40low-thermal-expansion ceramic particles VTA-13 CF-04 Good ExcellentExcellent CF-06 Good Excellent Excellent CF-07 Excellent Excellent GoodVTA-32 CF-04 Good Good Good CF-06 Good Good Good CF-07 Good Good Good

TABLE 8 Evaluated shear stress of bonded articles between nickelsubstrates Amount (in volume percent) of 70 60 50 lead-free low-meltingglass composition Amount (in volume percent) of 30 40 50low-thermal-expansion ceramic particles VTA-13 CF-03 Good Excellent GoodCF-06 Good Good Excellent CF-07 Good Excellent Excellent VTA-32 CF-03Good Excellent Good CF-06 Good Good Excellent CF-07 Good ExcellentExcellent

TABLE 9 Evaluated shear stress of bonded articles between ironsubstrates Amount (in volume percent) of 70 80 50 lead-free low-meltingglass composition Amount (in volume percent) of 30 40 50low-thermal-expansion ceramic particles VTA-13 CF-01 Excellent ExcellentExcellent CF-02 Excellent Excellent Excellent CF-03 Good Good ExcellentVTA-32 CF-01 Excellent Excellent Excellent CF-02 Excellent ExcellentExcellent CF-03 Good Good Excellent

TABLE 10 Evaluated shear stress of bonded articles between soda-limeglass substrates Amount (in volume percent) of 60 50 40 30 lead-freelow-melting glass composition Amount (in volume percent) of 40 50 60 70low-thermai-expansion ceramic particles VTA-13 CF-01 Good Excellent GoodRejected CF-02 Good Excellent Good Rejected VTA-32 CF-01 Good ExcellentGood Rejected CF-02 Good Excellent Good Rejected

TABLE 11 Evaluated shear stress of bonded articles between aluminumoxide substrates Amount (in volume percent) of 60 50 40 30 lead-freelow-melting glass composition Amount (in volume percent) of 40 50 60 70low-thermal-expansion ceramic particles VTA-13 CF-01 Good Excellent GoodRejected CF-02 Good Excellent Good Rejected VTA-32 CF-01 Good ExcellentGood Rejected CF-02 Good Excellent Good Rejected

With reference to Table 5, the tested bonded articles between aluminum(Al) substrates employed the low-thermal-expansion ceramic particlesCF-04 or CF-05 (see Table 4) in different contents (blending amounts) of0 to 20 volume percent and employed the lead-free low-melting glasscomposition VTA-13 or VTA-32 in different contents of 100 to 80 volumepercent. The data demonstrated that these samples offered excellentresults under all the conditions, had a very high bond strength and verygood adhesion to aluminum (Al), and offered similar results even whenusing either of VTA-13 and VTA-32. With reference to Table 6, the bondedarticles between silver (Ag) substrates also offered excellent results,and the constitutive glass frits had a very high bond strength and verygood adhesion to silver (Ag), as with aluminum (Al).

With reference to Table 7, the tested bonded articles between copper(Cu) substrates employed the low-thermal-expansion ceramic particlesCF-04, CF-05, and CF-06 (see Table 4) in different contents (blendingamounts) of 20 to 40 volume percent and employed the lead-freelow-melting glass compositions VTA-13 and VTA-32 in different contentsof 80 to 60 volume percent. These samples offered good or higher resultsunder all the conditions. The glass frits employing VTA-13, when furthercontaining an increasing content (amount) of CF-04 or CF-06, offered ahigher bond strength and better adhesion to copper (Cu). This is becausethe glass frits came to have a coefficient of thermal expansionconformable to that of copper (Cu). In contrast, the glass frits usingCF-07 offered opposite results. This is because CF-07 has a very lowcoefficient of thermal expansion as compared with CF-04 and CF-06. Incontrast, the samples using VTA-32 did not offer a significantdifference in shear stress among blending ratios, unlike the samplesusing VTA-13. This is probably because the samples using VTA-32 wereheated and bonded at a higher temperature, and this accelerated theoxidation of copper (Cu) by VTA-32.

With reference to Table 8, the tested bonded articles between nickel(Ni) substrates employed low-thermal-expansion ceramic particles CF-03,CF-06, and CF-07 (see Table 4) in different contents (amounts) of 30 to50 volume percent and employed the lead-free low-melting glasscompositions VTA-13 and VTA-32 in different contents of 70 to 50 volumepercent. The samples offered good or higher results under all theconditions and offered similar results even when using either of VTA-13and VTA-32. The samples using CF-03, when containing CF-03 in a content(amount) of 40 volume percent, had a highest shear stress and offered avery high bond strength and very good adhesion to the nickel (Ni)substrates. The data demonstrated that the samples using CF-06 and CF-07in increasing contents (amounts) had a higher (increasing) shear stressand offered a higher bond strength and better adhesion to the nickel(Ni) substrates. This is probably because the samples came to have acoefficient of thermal expansion conformable to that of nickel (Ni).

With reference to Table 9, the tested bonded articles between iron (Fe)substrates employed the low-thermal-expansion ceramic particles CF-01 toCF-03 (see Table 4) in different contents (amounts) of 30 to 50 volumepercent and employed the lead-free low-melting glass compositions VTA-13and VTA-32 in different contents of 70 to 50 volume percent. The samplesoffered good or higher results under all the conditions and offeredsimilar results even when using either of VTA-13 and VTA-32. The datademonstrated that the samples using CF-01 and CF-02 had a high shearstress regardless of their contents (amounts) and offered a very highbond strength and very good adhesion to iron (Fe). This is probablybecause as follows. CF-01 and CF-02 have coefficients of thermalexpansion as ones of the lowest in the ceramic particles in Table 4 andstill have good wettability with and adhesion to VTA-13 and VTA-32. Theresulting low-temperature sealing glass frits can easily haveefficiently lowered coefficients of thermal expansion conformable to thecoefficient of thermal expansion of the iron (Fe) substrates. The dataalso demonstrated that the samples using CF-03 did not have sosignificant results as compared with the samples using CF-01 and CF-02,had an increasing shear stress, and offered a higher bond strength andbetter adhesion to the iron (Fe) substrate with an increasing content(amount) of CF-03. This is also because the samples came to have acoefficient of thermal expansion conformable to that of iron (Fe).

With reference to Table 10, the tested bonded articles between soda-limeglass substrates employed the low-thermal-expansion ceramic particlesCF-01 and CF-02 (see Table 4) in different contents (amounts) of 40 to70 volume percent and employed the lead-free low-melting glasscompositions VTA-13 and VTA-32 in different contents of 60 to 30 volumepercent. There was little difference in shear stress between CF-01 andCF-02, and between VTA-13 and VTA-32. The samples offered good or higherresults under all the conditions when containing CF-01 or CF-02 in thecontent (amount) of 40 to 60 volume percent and VTA-13 or VTA-32 in thecontent (amount) of 60 to 40 volume percent. The samples, whencontaining CF-01 or CF-02 in a content of 50 volume percent, had alargest shear stress and offered a very high bond strength and very goodadhesion to the soda-lime glass substrates. The samples, when containingCF-01 or CF-02 in the content (amount) of 60 volume percent or more, hada lower shear stress and were evaluated as rejected at a content of 70volume percent. This is because as follows. Assume that glass fritscontain VTA-13 or VTA-32 in an excessively low content (amount) withrespect to the content (amount) of CF-01 or CF-02. In this case, theglass frits soften and flow unsatisfactorily as low-temperature sealingglass frits, have inferior adhesion and bonding properties to thesoda-lime glass substrates, and fail to have a good shear stress. Withreference to Table 11, the bonded articles between aluminum oxide(Al₂O₃) substrates also offered shear stress evaluation results similarto those of the bonded articles between soda-lime glass substrates. Thisis because the aluminum oxide (Al₂O₃) and soda-lime glass havecoefficients of thermal expansion at similar levels. These results andconsiderations demonstrated that it is important to designlow-temperature sealing glass frits to contain the lead-free low-meltingglass composition according to the embodiment of the present inventionin a content (amount) of 40 volume percent or more, andlow-thermal-expansion ceramic particles in the content (amount) of 60volume percent or less. The tested bonding between the soda-lime glasssubstrates and between the aluminum oxide (Al₂O₃) substrates employedthe low-temperature sealing glass paste containing diethylene glycoln-butyl ether acetate as a solvent and ethyl cellulose as a resinbinder. For further testing, bonded articles were prepared by preparinga low-temperature sealing glass paste containing α-terpineol as asolvent and isobornylcyclohexanol as a viscosity modifier instead of theabove components, and performing heating in the air. The prepared bondedarticles were subjected to shear stress evaluation in a similar mannerand were found to readily have a higher shear stress. This is becausethe low-temperature sealing glass frit at the junction (bonded portion)contained smaller amounts of residual air bubbles. The data indicatethat α-terpineol is as the solvent effective not only in an inert gasatmosphere, but also in the air.

These data demonstrated that the low-temperature sealing glass fritaccording to the embodiment of the present invention effectivelycontains 40 to 100 volume percent of the lead-free low-melting glasscomposition according to the embodiment of the present invention and 0to 60 volume percent of the low-thermal-expansion ceramic particles. Thedata also demonstrated that the low-thermal-expansion ceramic particlescan be selected from zirconium phosphate tungstate (Zr₂(WO₄) (PO₄)₂),quartz glass (SiO₂), zirconium silicate (ZrSiO₄), aluminum oxide(Al₂O₃), mullite (3Al₂O₃.2SiO₂), and niobium oxide (Nb₂O₅) each inparticle form. In particular, the low-temperature sealing glass fritmore effectively contains zirconium phosphate tungstate (Zr₂(WO₄)(PO₄)₂) and/or a compound containing mainly zirconium phosphatetungstate (Zr₂(WO₄) (PO₄)₂) so as to still less undergo thermalexpansion. The content of this component is preferably 30 to 50 volumepercent. The low-temperature sealing glass paste according to theembodiment of the present invention may contain a solvent that can beselected from α-terpineol and diethylene glycol n-butyl ether acetate,of which α-terpineol is more effective.

Experimental Example 4

In this experimental example, conductive materials containing thelead-free low-melting glass composition according to the embodiment ofthe present invention and metal particles were prepared. Pairs of metalsubstrates of the same kind were bonded using the conductive materials,and how the metal substrates were bonded was evaluated with electricresistance (contact resistance) between the metal substrates. Thelead-free low-melting glass composition used herein was VTA-31 (seeTables 2 and 3), and the metal particles were four different particlesof silver (Ag), copper (Cu), aluminum (Al), and tin (Sn). The metalsubstrates were substrates of aluminum (Al), silver (Ag), and copper(Cu). Each evaluation sample was prepared in the following manner.Initially, a conductive glass paste containing the lead-free low-meltingglass composition particles, the metal particles, and a solvent wasprepared. This was applied to both of a pair of the substrates, dried,preliminarily fired. The both substrates were then laminated, heated,and thereby bonded.

(Preparation of Conductive Glass Paste)

The lead-free low-melting glass composition particles, the metalparticles, and the solvent were blended and mixed to give eachconductive glass paste. The lead-free low-melting glass compositionparticles used herein were VTA-31 in the form of particles having aparticle diameter of about 10 μm. The metal particles were spherical(globular) silver (Ag) particles having an average particle diameter ofabout 1.5 μm, spherical copper (Cu) particles having an average particlediameter of about 20 μm, spherical aluminum (Al) particles having anaverage particle diameter of about 10 μm, and spherical tin (Sn)particles having an average particle diameter of about 25 μm. Thesolvent was α-terpineol, added with isobornylcyclohexanol as a viscositymodifier. The lead-free low-melting glass composition particles and themetal particles were blended in five different blending ratios (involume percent) of 100:0, 80:20, 60:40, 40:60, and 20:80 to preparecorresponding conductive glass pastes. The conductive glass pastes wereprepared so as to have a solids content of about 80 mass percent. The“solids content” refers to the total content of the lead-freelow-melting glass composition particles and the metal particles.

(Preparation of Evaluation Sample)

The contact resistance between each pair of metal substrates wasmeasured by preparing an evaluation sample as in Experimental Example 3by the procedure of Experimental Example 3. Specifically, thisexperimental example employed the evaluation sample and its preparationmethod similar to those illustrated in FIG. 2.

Initially, a cylindrical metal substrate 1′ including a bonding plane 2′and having a diameter of 5 mm and a thickness of 5 mm was prepared (step(a)).

Next, the bonding plane 2′ of the cylindrical metal substrate 1′ wascoated with a low-temperature sealing glass paste 3′ by dispensing (step(b)).

The resulting article was dried at 120° C. to 150° C. in the air. Thiswas placed in an electric furnace, heated up to 220° C. at a rate oftemperature rise of 10° C. per minute in an inert gas (nitrogen orargon), held for 15 minutes, heated up to a temperature higher than thesoftening point T_(s) of the contained lead-free low-melting glasscomposition by about 40° C. at the same rate of temperature rise asabove, held for 10 minutes, and thereby formed a low-temperature sealingglass frit 4′ on the bonding plane 2′ of the cylindrical metal substrate1′ (step (c)). This experimental example employed the lead-freelow-melting glass composition VTA-31, and the heating was performed upto a temperature of 280° C. that is higher than the softening pointT_(s) by about 40° C. The resulting article was placed on a plate metalsubstrate 5′ having a thickness of 1 to 3 mm and including a material ofthe same type with the cylindrical metal substrate 1′, fastened thereonwith a heat-resistant clip, heated up to 280° C. in an inert gas(nitrogen) at a rate of temperature rise of 10° C. per minute held for30 minutes, and yielded a bonded article (step (d)).

The bonded article was subjected to measurement of contact resistancebetween metal substrates.

(Evaluation of Bonding)

Each of the prepared bonded articles was examined to measure contactresistance (electric resistance) between the metal substrates by thefour probe method. As a comparison, bonding of metal substrates using alead-free tin solder was also performed. The contact resistance ofbonded articles bonded with the solder was 3.2×10⁻³ Ω/mm² for bondingbetween the aluminum (Al) substrates (Al/Al bonding), 4.7×10⁻⁶ Ω/mm² forbonding between the silver (Ag) substrates (Ag/Ag bonding), and 5.0×10⁻⁶Ω/mm² for bonding between the copper (Cu) substrates (Cu/Cu bonding).The Al/Al bonding had a contact resistance higher than those of theAg/Ag bonding and the Cu/Cu bonding by about three orders of magnitude.This is because a natural oxide layer having a high electric resistancewas formed on the Al substrate surfaces.

Typically, Al/Al bonding, Ag/Ag bonding, and Cu/Cu bonding wereperformed using conductive materials each containing the lead-freelow-melting glass composition VTA-31 and Ag metal particles. FIG. 3illustrates how the contact resistance varies depending on the contentsof VTA-31 and Ag. In the Al/Al bonding and Ag/Ag bonding, the contactresistance reached the order of 10⁻⁶ Ω/mm² within a wide range of thecontents of VTA-31 and Ag with little dependency on the contents. Incontrast, in the Cu/Cu bonding, the contact resistance decreased with anincreasing Ag content and a decreasing VTA-31 content and reached theorder of 10⁻⁶ Ω/mm² at the Ag content of about 30 volume percent or moreand the VTA-31 content of about 70 volume percent or less. In the Al/Albonding, VTA-31 reacted with the Al substrates to remove a natural oxidelayer on the Al substrate surfaces and to form Al₃V or another alloybetween Al and V at the interface. VTA-31, as reacted with Al to releaseV (vanadium), underwent precipitation of metal Ag therefrom. When the Alsubstrates were bonded at a small distance therebetween, theprecipitated metal Ag established connection between the Al substrates.For this reason, even a glass paste containing not Ag particles, butVTA-31 alone offered a low contact resistance. In addition, testing datademonstrated that, when a glass paste further containing Ag particleswas used, VTA-31 reacts with the Ag particles to promote the neckingamong the Ag particles. This is probably because Ag has certainsolubility in VTA-31 and, upon bonding by heating, is dissolved inVTA-31 that softens and flows as a result of heating. Ag is precipitatedwith temperature fall and causes necking among the Ag particles. In theAl/Al bonding, the above-mentioned two reactions relating to thelead-free low-melting glass composition according to the embodiment ofthe present invention probably contributed to a contact resistance onthe order of 10⁻⁶ Ω/mm² in wide ranges of the VTA-31 content and Agcontent with little dependency on the contents. The contact resistancein the Ag/Ag bonding behaved in a similar manner to the Al/Al bonding.This is because the second reaction in the Al/Al bonding, namely, thereaction between the Ag particles and VTA-31 also occurred with respectto the Ag substrates, and metal Ag was precipitated at the interfacebetween the Ag substrate and VTA-31. When the Ag substrates were bondedwith a small distance therebetween, the precipitated metal Agestablished connection between the Ag substrates. For this reason, evena glass paste containing not Ag particles, but VTA-31 alone offered alow contact resistance. Even when a conductive glass paste furthercontaining Ag particles was used, VTA-31 promoted necking among the Agparticles as in the Al/Al bonding, and this achieved a contactresistance on the order of 10⁻⁶ Ω/mm² in wide ranges of VTA-31 contentand Ag content with little dependency on the contents. In the Cu/Cubonding, the necking of the Ag particles mainly contributes to theformation of conduction paths, unlike the Al/Al bonding and Ag/Agbonding. Thus, the contact resistance decreased with an increasingcontent of Ag particles and reached the order of 10⁻⁶ Ω/mm² at a contentof Ag particles of 30 volume percent or more.

Separately, Al/Al bonding, Ag/Ag bonding, and Cu/Cu bonding wereperformed using conductive materials each containing the lead-freelow-melting glass composition VTA-31 and Cu metal particles. FIG. 4shows how the contact resistance varies depending on the contents ofVTA-31 and Cu in the conductive materials. In the Al/Al bonding andAg/Ag bonding, the contact resistance gradually increased with anincreasing Cu content and a decreasing VTA-31 content and significantlydecreased at a Cu content of 40 volume percent or more and a VTA-31content of 60 volume percent or less. In contrast, the contactresistance reached the order of 10⁻⁶ Ω/mm² at the Cu content of about 30volume percent or less and the VTA-31 content of about 70 volume percentor more. In the Cu/Cu bonding, the contact resistance once decreasedwith an increasing Cu content and a decreasing VTA-31 content, butsignificantly increased at a Cu content of 40 volume percent or more anda VTA-31 content of 60 volume percent or less, as in the Al/Al bondingand Ag/Ag bonding. The Cu/Cu bonding offered a higher contact resistanceas compared to the Al/Al bonding and Ag/Ag bonding. This phenomenonoccurred because VTA-31 softens, flows, and thereby oxidizes the Cuparticles and Cu substrates to form an oxide layer on their surfaces.

Al/Al bonding, Ag/Ag bonding, and Cu/Cu bonding were also performedusing conductive materials each containing the lead-free low-meltingglass composition VTA-31 and Al metal particles. FIG. 5 illustrates howthe contact resistance varies depending on the contents of VTA-31 and Alin the conductive materials. In the Al/Al bonding, Ag/Ag bonding, andCu/Cu bonding using VTA-31 and the Al particles, the contact resistancevaried and behaved in a similar manner as in the samples using Cu metalparticles, but was lower as compared with the samples using the Cu metalparticles. In particular in the Al/Al bonding and Ag/Ag bonding, thecontact resistance reached the order of 10⁻⁶ Ω/mm² at an Al content ofabout 60 volume percent or less and a VTA-31 content of about 40 volumepercent or more. In the Cu/Cu bonding, the contact resistance was higheras compared with the Al/Al bonding and Ag/Ag bonding, as in the samplesusing the Cu particles, but lower as compared with the samples using theCu particles. This is because the Cu particles are more susceptible tooxidation by the lead-free low-melting glass composition according tothe embodiment of the present invention. The samples herein had a highercontact resistance as compared with the samples using the Ag metalparticles at the Al content of 40 volume percent or more and the VTA-31content of 60 volume percent or less. This is because the Ag particlesare more susceptible to necking by the lead-free low-melting glasscomposition as compared with the Al particles.

Al/Al bonding, Ag/Ag bonding, and Cu/Cu bonding were also performedusing conductive materials each containing the lead-free low-meltingglass composition VTA-31 and Sn metal particles. FIG. 6 illustrates howthe contact resistance varies depending on the contents of VTA-31 and Snin the conductive materials. The contact resistance in the Ag/Ag bondingand Cu/Cu bonding using VTA-31 and the Sn particles offered similarresults to the samples using the Ag metal particles. In the Ag/Agbonding, the contact resistance reached the order of 10⁻⁶ Ω/mm² in wideranges of contents of VTA-31 and Sn with little dependency on thecontents. In the Cu/Cu bonding, the contact resistance reached the orderof 10⁻⁶ Ω/mm² at the Sn content of 20 volume percent or more and theVTA-31 content of 80 volume percent or less. These are because metal Snhas a melting point of 232° C., and particles thereof melt upon bondingby heating to bond to the Ag substrates or Cu substrates, as with asolder. In the Al/Al bonding, the Al substrate surface bears a naturaloxide layer. Owing to this, the bonding with the solder failed to givegood conductivity, but the samples containing both VTA-31 and Sn couldoffer a lower contact resistance by the presence of VTA-31. The contactresistance behaved as follows. The contact resistance increased with anincreasing Sn content and a decreasing VTA-31 content, but decreased atthe Sn content of about 60 volume percent or more and the VTA-31 contentof about 40 volume percent or less.

These results and considerations demonstrate that the lead-freelow-melting glass composition according to the embodiment of the presentinvention can be expanded into conductive materials and correspondingconductive glass pastes so as to form conductive junctions to establishconnection (conduction) between metal substrates. In this experimentalexample, VTA-31 has been described representatively as a lead-freelow-melting glass composition according to an embodiment of the presentinvention. Obviously, other lead-free low-melting glass compositionsaccording to embodiments of the present invention can also developsimilar performance. Likewise, Ag, Cu, Al, and Sn have been describedrepresentatively as metal particles to be contained in conductivematerials or corresponding conductive glass pastes. It should be noted,however, that the present invention can provide similar performance onnot only these metals, but also on alloys of them. Solder is generallyapplied to form a conductive junction between metal substrates. Inconsideration of differentiation from the solder, Ag particles and Alparticles are effective as the metal particles to be contained in theconductive material or in the corresponding conductive glass paste. Thesolder hardly establish good conductive junction on Al substrates andother metal substrates bearing a natural oxide layer on the surface. Incontrast, the conductive material and conductive glass paste accordingto the embodiments of the present invention can establish goodconductive bonding (conductive junction) even on such metal substrates.This is archived by the action of the constitutive lead-free low-meltingglass composition according to the embodiment of the present invention.

The data demonstrated that the conductive material and correspondingconductive glass paste according to embodiments of the present inventionare very effective for the low-temperature formation of conductivejunctions in various electronic components. When a portion to be bondedor sealed may have conductivity, the conductive material andcorresponding conductive glass paste according to embodiments of thepresent invention are usable also as a low-temperature sealing glassfrit and a corresponding low-temperature sealing glass paste asdescribed in Experimental Example 3.

Experimental Example 5

In this experimental example, conductive materials each containing alead-free low-melting glass composition according to the embodiment ofthe present invention and metal particles were prepared. Using theconductive materials, an electrode/interconnection was formed ondifferent substrates and was examined to evaluate electric resistance(interconnect resistance) and adhesion to the substrates. The lead-freelow-melting glass composition and the metal particles used herein wererespectively VTA-36 (see Tables 2 and 3) and silver (Ag) particles. Thesubstrates used were an aluminum oxide (Al₂O₃) substrate, a borosilicateglass substrate, a silicon (Si) substrate, a ferrite substrate, and apolyimide substrate. Each evaluation sample was prepared in thefollowing manner. Initially, a conductive glass paste containing thelead-free low-melting glass composition particles, the metal particles,and a solvent was prepared. The conductive glass paste was applied toeach substrate, dried, and preliminarily fired to form anelectrode/interconnection.

(Preparation of Conductive Glass Paste)

The lead-free low-melting glass composition particles, the metalparticles, and the solvent were blended, mixed, and yielded a series ofconductive glass pastes. The lead-free low-melting glass compositionparticles used herein were VTA-36 particles having a particle diameterof about 10 μm, and the metal particles were spherical silver (Ag)particles having an average particle diameter of about 1.5 μm. Thesolvent was α-terpineol, added with isobornylcyclohexanol as a viscositymodifier. Table 12 shows blending ratios between the lead-freelow-melting glass composition VTA-36 particles and the Ag metalparticles. Seven different conductive glass pastes were prepared in theblending ratios given in Table 12. The conductive glass pastes wereprepared so as to have a solids content of about 80 mass percent. The“solids content” refers to the total content of the lead-freelow-melting glass composition particles and the metal particles.

(Preparation of Evaluation Sample)

Using the seven conductive glass pastes DH-01 to DH-07 as in Table 12,electrodes/interconnections were formed in an interconnection patternillustrated in FIG. 7. With reference to FIG. 7, a substrate 6 usedherein was any of the aluminum oxide (Al₂O₃) substrate, borosilicateglass substrate, silicon (Si) substrate, ferrite substrate, andpolyimide substrate. Interconnections 7 to 13 correspond respectively toDH-01 to DH-07 in Table 12. Initially, the individual conductive glasspastes were applied onto each of the substrates by a screen processprinting to form patterns of a size of 2 mm by 30 mm, and dried at 120°C. to 150° C. in the air. The patterns in this process had a thicknessof 30 to 40 μm. This was placed in an electric furnace, heated up to220° C. at a rate of temperature rise of 10° C. per minute, held for 30minutes, further heated up to a temperature higher than the softeningpoint T_(s) of the corresponding lead-free low-melting glass compositionby about 50° C. at the same rate of temperature rise as above, held for20 minutes, and thereby formed interconnections 7 to 13 on the substrate6. This experimental example employed the lead-free low-melting glasscomposition VTA-36, and the samples were heated up to 300° C., i.e., atemperature higher than the softening point T_(s) by about 50° C.

(Evaluation of Interconnect Resistance)

As described above, the interconnections 7 to 13 were formed on eachsubstrate using the seven conductive glass pastes DH-01 to DH-07 havingblending ratios given in Table 12. The interconnect resistance of eachof the interconnections was measured by the four probe method.

TABLE 12 Content (amount) of lead-free low-melting glass composition andmetal particles in electrode/interconnection Lead-free low-melting Agmetal Electrode/ glass composition particles interconnection VTA-36 (in(in volume number volume percent) percent) Remarks DH-01 5 95Interconnection 7 in FIG. 7 DH-02 10 90 Interconnection 8 in FIG. 7DH-03 15 85 Interconnection 9 in FIG. 7 DH-04 20 80 Interconnection 10in FIG. 7 DH-05 30 70 Interconnection 11 in FIG. 7 DH-06 40 60Interconnection 12 in FIG. 7 DH-07 50 50 Interconnection 13 in FIG. 7

(Evaluation of Adhesion)

The interconnections 7 to 13 were subjected to a peel test to evaluateadhesion to the substrates. A peeling tape was applied to eachinterconnection on the substrate and then peeled off. A sample sufferingfrom neither peeling of the interconnection from the substrate nor breakwas evaluated as “accepted”. In contrast, a sample suffering frompeeling and/or break in the interconnection was evaluated as “rejected”.

Typically, interconnections were formed on each substrate usingconductive materials each containing the lead-free low-melting glasscomposition VTA-36 and the Ag metal particles. FIG. 8 illustrates howthe interconnect resistance of the interconnections varies depending onthe contents of VTA-36 and Ag in the conductive materials. The testedsubstrates were five substrates, i.e., an Al₂O₃ substrate, aborosilicate glass substrate, a Si substrate, a ferrite substrate, and apolyimide substrate. However, little difference in interconnectresistance among the substrates was found. The interconnect resistancedecreased with an increasing Ag content and a decreasing VTA-36 contentand reached the order of 10⁻⁶ Ωcm at the Ag content of 70 to 95 volumepercent and the VTA-36 content of 30 to 5 volume percent. Theinterconnect resistance reached its minimum level at the Ag content ofabout 85 to about 90 volume percent and the VTA-36 content of about 10to about 15 volume percent. The lead-free low-melting glass compositionaccording to the embodiment of the present invention can satisfactorilysoften and flow, and thereby promotes the necking of Ag particles uponthe interconnection formation, as is described above. Thus, the presentinvention enables the formation of electrodes/interconnections at such alow temperature (e.g., 300° C. in this experimental example), where theresulting electrodes/interconnections have a remarkably low interconnectresistance. The five different substrates, i.e., the Al₂O₃ substrate,borosilicate glass substrate, Si substrate, ferrite substrate, andpolyimide substrate were investigated in this experimental example. Itcan be easily surmised that the present invention is applicable also toother substrates.

Table 13 shows the peel test results of the interconnections formed onthe substrates. The samples were evaluated as accepted and offered agood adhesion with respect to any type of the substrates at a lead-freelow-melting glass composition having the VTA-36 content of 10 volumepercent or more and a Ag metal particles content of 90 volume percent orless, as is demonstrated by the data of DH-02 to DH-07 in Table 13.However, the samples suffered from an interconnection peeling, wereevaluated as rejected, and were considered to have an insufficientadhesion at the VTA-36 content of 5 volume percent and the Ag content of95 volume percent. These results demonstrated that the lead-freelow-melting glass composition in the conductive material satisfactorilysoftens and flows upon the interconnection formation and is therebybonded to and brought into intimate contact with the substrate; but thatthe glass composition, if present in an excessively low content,insufficiently comes into contact with the substrate. This demonstratedthat the conductive material preferably contains the lead-freelow-melting glass composition in the content of 10 volume percent ormore. It should be noted, however, that even a conductive materialcontaining the lead-free low-melting glass composition in the content of5 volume percent can sufficiently possibly offer a good adhesion if arefinement such as pressurizing upon the interconnection formation canbe made.

TABLE 13 Electrode/interconnection peel test results Electrode/ inter-Borosilicate connection Al₂O₃ glass Silicon Ferrite Polyimide numbersubstrate substrate substrate substrate substrate DH-01 RejectedRejected Rejected Rejected Rejected DH-02 Accepted Accepted AcceptedAccepted Accepted DH-03 Accepted Accepted Accepted Accepted AcceptedDH-04 Accepted Accepted Accepted Accepted Accepted DH-05 AcceptedAccepted Accepted Accepted Accepted DH-06 Accepted Accepted AcceptedAccepted Accepted DH-07 Accepted Accepted Accepted Accepted Accepted

As is demonstrated above, the lead-free low-melting glass compositionsaccording to the embodiment of the present invention can be expandedeffectively into conductive materials and corresponding conductive glasspastes to form electrodes/interconnections at a low temperature. In thisexperimental example, VTA-36 was used and described as a representativelead-free low-melting glass composition. Obviously, however, otherlead-free low-melting glass compositions according to embodiments of thepresent invention can develop performance at similar levels. Likewise,the Ag particles were used in this experimental example as metalparticles to be contained in conductive materials and correspondingconductive glass pastes. Also obviously, the present invention is notlimited thereto and can be applied also to Ag alloys, Cu, Al, and Sn,and alloys of them. The above evaluations and considerationsdemonstrated that the conductive materials and corresponding conductiveglass pastes according to embodiments of the present invention are veryeffective for the low-temperature formation ofelectrodes/interconnections in various electronic components.

Experimental Example 6

In this experimental example, vacuum-insulating double glass panels wereprepared representatively as a glass-sealed component according to anembodiment of the present invention. Specifically, the vacuum-insulatingdouble glass panels were prepared using a pair of soda-lime glasssubstrates, and a low-temperature sealing glass frit according to anembodiment of the present invention. Whether and how the low-temperaturesealing glass frit according to the embodiment of the present inventioncan be applied was evaluated. In this experimental example, alow-temperature sealing glass paste was used to form the low-temperaturesealing glass frit.

FIG. 9A is a schematic plan view of the prepared vacuum-insulatingdouble glass panel. FIG. 9B is an enlarged view of a cross-section takenalong the line A-A of FIG. 9A in a portion adjacent to a seal portion.

As illustrated in FIG. 9A, the vacuum-insulating double glass panelincludes a soda-lime glass substrate 15 and another soda-lime glasssubstrate 16 (see FIG. 9B) disposed as overlying the substrate 15 with agap (space). The panel also includes a seal portion 14 in acircumferential portion of the substrates 15 and 16. The panel includesplural spacers 18 between the two substrates 15 and 16. The spacers 18are two-dimensionally disposed and spaced uniformly. The soda-lime glasssubstrate 16 includes an evacuation port 20. The gap between the twosubstrates 15 and 16 has been evacuated through the evacuation port 20using a vacuum pump (not shown). The evacuation port 20 is capped with acap 21.

As illustrated in FIG. 9B, the panel includes a space (the gap) 17between the pair of soda-lime glass substrate 15 and 16 including theseal portion 14 in the peripheral portion (edge portion). The space 17is maintained under vacuum. The seal portion 14 has been sealed usingthe low-temperature sealing glass frit according to the embodiment ofthe present invention. The vacuum-insulating double glass panel can beexpanded typically into architectural windowpanes and doors ofcommercial-use refrigerators and freezers. The low-temperature sealingglass frit according to the embodiment of the present invention used toform the seal portion 14 contains, in addition to the lead-freelow-melting glass composition according to the embodiment of the presentinvention, low-thermal-expansion ceramic particles so as to have acoefficient of thermal expansion conformable to the coefficient ofthermal expansion of the soda-lime glass substrates 15 and 16. Thesoda-lime glass substrates 15 and 16 have heat resistance up to atemperature of about 500° C., and the seal portion 14 may be formed at atemperature equal to or lower than that temperature. The soda-lime glasssubstrates 15 and 16 are susceptible to failure upon rapid heating orrapid cooling. To prevent this, heating and cooling in the sealing haveto be performed gradually. The sealing is preferably performed at atemperature as low as possible so as to produce the vacuum-insulatingdouble glass panel with better productivity. In addition, the soda-limeglass substrates 15 and 16 are susceptible to failure upon deformation.To prevent this, the plural spacers 18 are disposed in the space 17maintained under vacuum. For allowing the space 17 to have an adequatethickness, it is effective, for example, to introduce spherical beads 19having approximately identical particle diameters into the spacers 18and the seal portion 14. The spacers 18 can be fixed using thelow-temperature sealing glass frit according to the embodiment of thepresent invention, as with the seal portion 14. For obtaining the space17 maintained under vacuum, the evacuation port 20 is previously formedin the soda-lime glass substrate 16, and the space 17 is evacuatedthrough the evacuation port 20 using a vacuum pump. After theevacuation, the evacuation port 20 is capped with the cap 21 so as tomaintain the space 17 under vacuum. The panel, when applied as anarchitectural windowpane, may further include a heat-reflecting film 22on the inner surface of the soda-lime glass substrate 15, where theheat-reflecting film 22 has been previously formed typically by vapordeposition.

The soda-lime glass substrates 15 and 16 used in this experimentalexample each had a size of 900 by 600 by 3 mm. The soda-lime glasssubstrate 15 bore the heat-reflecting film 22, and the soda-lime glasssubstrate 16 included the evacuation port 20. The panel included thespherical beads 19 having a diameter of a little under 200 μm in theseal portion 14 and the spacers 18 so as to allow the distance betweenthe soda-lime glass substrates 15 and 16, namely, the thickness of thespace 17, to be about 200 μm. The spherical beads 19 included soda-limeglass. The low-temperature sealing glass frit used in the seal portion14 included the lead-free low-melting glass composition VTA-39 (seeTables 2 and 3) and the low-thermal-expansion ceramic particles CF-01(see Table 4) in a blending ratio in volume percent of 50:50. Thespherical beads 19 were contained in the seal portion 14 in a content of1 volume percent with respect to the volume of the low-temperaturesealing glass frit; and were contained in the spacers 18 in a content of20 volume percent with respect to the volume of the low-temperaturesealing glass frit.

(Preparation of Low-Temperature Sealing Glass Paste)

The lead-free low-melting glass composition according to the embodimentof the present invention in the form of particles, thelow-thermal-expansion ceramic particles, and a solvent were blended,mixed, and yielded low-temperature sealing glass pastes. The lead-freelow-melting glass composition particles used herein were VTA-39particles having a particle diameter of about 10 μm; and thelow-thermal-expansion ceramic particles were CF-01 (zirconium phosphatetungstate) particles having a particle diameter of about 30 μm. Thesolvent was α-terpineol, added with isobornylcyclohexanol as a viscositymodifier. The lead-free low-melting glass composition particles VTA-39and the low-thermal-expansion ceramic particles CF-01 were blended in aratio in volume percent of 50:50, and the low-temperature sealing glasspastes were prepared so as to have a solids content of 75 to 80 masspercent, where the “solids content” refers to the total content ofVTA-39 and CF-01. The low-temperature sealing glass pastes furthercontained soda-lime glass spherical beads having a particle diameter ofabout 180 to about 200 μm in a content of 1 volume percent for thelow-temperature sealing use and 20 volume percent for the spacers. Thecontents herein are each with respect to the solids content.

(Preparation of Vacuum-Insulating Double Glass Panel)

The vacuum-insulating double glass panel was prepared in thisexperimental example by a method that will be described with referenceto FIGS. 10A to 12.

FIG. 10A illustrates the soda-lime glass substrate 16 bearing the sealportion 14 and the spacers 18, where the glass substrate 16 is toconstitute the vacuum-insulating double glass panel illustrated in FIGS.9A and 9B.

As illustrated in FIG. 10A, the prepared low-temperature sealing glasspastes were applied to the peripheral portion (corresponding to the sealportion 14) and the inside (corresponding to the spacers 18) of thesoda-lime glass substrate 16 each by dispensing and dried at 120° C. to150° C. in the air. The resulting article was heated up to 220° C. at arate of temperature rise of 7° C. per minute in the air, held for 30minute, further heated up to 300° C. at the same rate of temperaturerise as above, and held for 30 minutes to allow the seal portion 14 andthe spacers 18 to be bonded to the soda-lime glass substrate 16.

FIG. 10B is a cross-sectional view taken along the line A-A of FIG. 10A.As illustrated in FIG. 10B, the seal portion 14 and the spacers 18 eachinclude the spherical bead 19.

FIG. 11A illustrates the soda-lime glass substrate 15 to constitute thevacuum-insulating double glass panel in FIG. 9B. FIG. 11B is across-sectional view taken along the line A-A of FIG. 11A.

As illustrated in FIGS. 11A and 11B, the soda-lime glass substrate 15bears the heat-reflecting film 22 on one side thereof.

FIG. 12 illustrates a final step of the method for preparing thevacuum-insulating double glass panel illustrated in FIGS. 9A and 9B.

With reference to FIG. 12, the soda-lime glass substrates 15 and 16 werefaced toward each other, aligned, and fastened with pluralheat-resistant clips. This was subjected to a heat treatment withevacuation and sealed.

FIG. 13 is a graph illustrating a sealing temperature profile in theheat treatment.

According to the sealing temperature profile in FIG. 13, the panel washeated up to a temperature adjacent to the softening point of the usedlead-free low-melting glass composition. In this experimental example,the panel was heated up to 250° C. equal to the softening point ofVTA-39 at a rate of temperature rise of 7° C. per minute in the air andheld for 30 minutes. While evacuating the inside through the evacuationport 20 using a vacuum pump, the panel was heated up to 280° C. at arate of temperature rise of 7° C. per minute, and held for 30 minutes tobe sealed.

As illustrated in FIG. 12, the seal portion 14 and the spacers 18 werecompressed and came into intimate contact with the two soda-lime glasssubstrates 15 and 16. The evacuation port 20 was then capped with thecap 21 and yielded a vacuum-insulating double glass panel. In thisexperimental example, ten vacuum-insulating double glass panels wereprepared in the above manner.

(Evaluation Results of Prepared Vacuum-Insulating Double Glass Panels)

Initially, the ten vacuum-insulating double glass panels prepared inthis experimental example were visually inspected. As a result, theywere found to have no visual defects such as fracture or cracking. Thespherical beads 19 in the seal portion 14 and in the spacers 18 allowedthe soda-lime glass substrates 15 and 16 to be held at an approximatelyuniform distance (thickness of the space therebetween). Specifically,the obtained vacuum-insulating double glass panel had a predeterminedspace 17. The panel was further subjected to a helium leak test and wasfound that the panel inside was maintained under vacuum, and the panelperipheral portion was hermetically sealed.

For the determination of the reliability of the seal portion 14, threeof the prepared vacuum-insulating double glass panels were immersed inwarm water at 50° C. for 30 days. As a result, it was found that theinside of all the three panels could be maintained under vacuum withoutmigration of water thereinto. Other three of the vacuum-insulatingdouble glass panels were subjected to 1000 cycles of a thermal cycletest in the range of −50° C. to +100° C. Also in this test, all thethree panels could maintain the inside under vacuum. These resultsdemonstrated as follows. Assume that the low-temperature sealing glassfrit and/or corresponding low-temperature sealing glass paste accordingto the embodiment of the present invention is applied to avacuum-insulating double glass panel. In this case, thevacuum-insulating double glass panel can include a seal portion offeringsatisfactory thermal insulation and having high reliability. Inaddition, the low-temperature sealing glass frit and/or correspondinglow-temperature sealing glass paste according to the embodiment of thepresent invention, when used, enables sealing to be performed at aremarkably low temperature and can significantly contribute to betterproductivity of such vacuum-insulating double glass panels.

As above, a vacuum-insulating double glass panel has been described inthis experimental example representatively as a glass-sealed componentaccording to an embodiment of the present invention. Specifically, thelow-temperature sealing glass frit and/or corresponding low-temperaturesealing glass paste containing the lead-free low-melting glasscomposition according to the embodiment of the present invention wasapplied to the vacuum-insulating double glass panel. The resultsdemonstrated that the low-temperature sealing glass frit andcorresponding low-temperature sealing glass paste containing thelead-free low-melting glass composition according to the embodiment ofthe present invention can be effectively applied to a seal portion of aglass-sealed component and provides a glass-sealed component havingreliability and productivity both at satisfactory levels. Obviously, theglass frit and corresponding glass paste can be effectively expandedalso into glass-sealed components other than the vacuum-insulatingdouble glass panel.

Experimental Example 7

In this experimental example, a display was prepared representatively asa glass-sealed component according to the embodiment of the presentinvention. Whether and how the low-temperature sealing glass fritaccording to the embodiment of the present invention is applicable wasdetermined and evaluated. The display included a multiplicity of organiclight-emitting diodes (OLEDs) between a pair of borosilicate glasssubstrates. This experimental example employed a low-temperature sealingglass paste to form the low-temperature sealing glass frit.

FIG. 14A is a schematic plan view of an OLED display according to anembodiment of the present invention. FIG. 14B is a cross-sectional viewtaken along the line A-A of FIG. 14A.

With reference to FIG. 14A, the OLED display includes a borosilicateglass substrate 23, another borosilicate glass substrate (see FIG. 14B)disposed as overlying the borosilicate glass substrate 23 with a gap,and a seal portion 14 formed using the low-temperature sealing glassfrit according to the embodiment of the present invention in aperipheral portion of the borosilicate glass substrates 23 and 24. TheOLED display includes OLEDs 25 between the borosilicate glass substrates23 and 24.

The OLEDs 25 are susceptible to deterioration by the presence of waterand/or oxygen. To prevent this, it is important for the peripheralportion, i.e., the seal portion 14 of the borosilicate glass substrates23 and 24 to be hermetically sealed with the low-temperature sealingglass frit containing the lead-free low-melting glass compositionaccording to the embodiment of the present invention. Thelow-temperature sealing glass frit according to the embodiment of thepresent invention used in the seal portion 14 contains, in addition tothe lead-free low-melting glass composition according to the embodimentof the present invention, low-thermal-expansion ceramic particles so asto have a coefficient of thermal expansion conformable to thecoefficient of thermal expansion of the borosilicate glass substrates 23and 24 as much as possible. The low-temperature sealing glass frit to beapplied to the seal portion 14 in this experimental example included thelead-free low-melting glass composition VTA-35 (see Tables 2 and 3) andthe low-thermal-expansion ceramic particles CF-02 (see Table 4) in aratio in volume percent of 45:55. The low-temperature sealing glass fritin this experimental example was formed from a low-temperature sealingglass paste further containing high viscosity α-terpineol as a solvent.

(Preparation of Low-Temperature Sealing Glass Paste)

The lead-free low-melting glass composition according to the embodimentof the present invention in the form of particles, thelow-thermal-expansion ceramic particles, and the solvent were blended,mixed, and yielded the low-temperature sealing glass paste. Thelead-free low-melting glass composition particles used herein wereVTA-35 particles having an average particle diameter of about 1 μm, andthe low-thermal-expansion ceramic particles were CF-02 particles havingan average particle diameter of about 3 μm. CF-02 is a compoundincluding mainly zirconium phosphate tungstate. The solvent wasα-terpineol, added with isobornylcyclohexanol as a viscosity modifier.The low-thermal-expansion ceramic particles CF-02 contained irontungstate (FeWO₄) in the zirconium phosphate tungstate particles so asto efficiently absorb a red semiconductor laser beam to thereby generateheat, as described later. The low-temperature sealing glass paste wasprepared so as to contain the lead-free low-melting glass compositionVTA-35 particles and the low-thermal-expansion ceramic particles CF-02in a blending ratio in volume percent of 45:55 and to have a solidscontent of about 80 mass percent, where the “solids content” refers tothe total content of VTA-35 and CF-02.

(Preparation of Organic Light-Emitting Diode (OLED) Display)

The OLED display in this experimental example was prepared by a methodas illustrated in FIGS. 15A to 17.

FIG. 15A illustrates one of a pair of substrates in the OLED display.FIG. 15B is a cross-sectional view taken along the line A-A of FIG. 15A.

As illustrated in FIG. 15A, the prepared low-temperature sealing glasspaste was applied to a peripheral portion of the borosilicate glasssubstrate 23 by a screen process printing and dried at 120° C. to 150°C. in the air. This was heated up to 220° C. at a rate of temperaturerise of 7° C. per minute in the air, held for 30 minutes, further heatedup to 300° C. at the same rate of temperature rise as above, and heldfor 30 minutes. This gave the seal portion 14 in the peripheral portionof the borosilicate glass substrate 23. The seal portion 14 was formedin the peripheral portion of the borosilicate glass substrate 23 so asto have a line width of about 2 mm and a thickness after firing of about15 μm.

FIG. 16A illustrates the other of the pair of substrates to constitutethe OLED display. FIG. 16B is a cross-sectional view taken along theline A-A of FIG. 16A.

As illustrated in these figures, a multiplicity of OLEDs 25 was formedon the borosilicate glass substrate 24. The number of the OLEDs 25corresponds to the number of picture elements. As illustrated in FIG.17, the borosilicate glass substrate 24 bearing the OLEDs 25 wasarranged to face the borosilicate glass substrate 23 bearing the sealportion 14, and a laser beam 26 was applied in an inert gas (nitrogen)from the borosilicate glass substrate 23 side toward the seal portion14. The laser beam 26 used herein was a red semiconductor laser beamhaving a wavelength of 805 nm so that the laser beam is efficientlyabsorbed by the lead-free low-melting glass composition and sealingglass frit according to the embodiment of the present invention. Theabsorbed laser beam may contribute to heat generation and thereby allowthe lead-free low-melting glass composition to readily soften and flow.The laser beam 26 traveled at a speed of 10 mm/second in the peripheralportion to bond the borosilicate glass substrates 23 and 24 in theperipheral portion through the seal portion 14. Thus, the OLED displaywas prepared.

In this experimental example, five OLED displays were prepared in theabove manner. The sealing was performed using the laser beam so as toprevent or mitigate thermal damage on the OLEDs and to provide betterproductivity.

(Evaluation Results of Prepared Organic Light-Emitting Diode (OLED)Displays)

Initially, one of the prepared OLED displays was subjected to a lightingtest and found to properly illuminate. The sample OLED display also hadgood adhesion and bonding properties in the seal portion. Next, the OLEDdisplay was subjected to a high-humidity/temperature test (saturatedpressure cooker test) at 120° C., 100% relative humidity, and 202 kPafor one day, 3 days, and 7 days. As a comparative example, an OLEDdisplay including a portion sealed with a resin was also subjected tothe test. The resin-sealed portion had a line width of about 5 mm and athickness of about 15 μm. Both the OLED displays properly illuminated inthe one-day high-humidity/temperature test, but the resin-sealed OLEDdisplay suffered from significant deterioration in illumination in 3-dayand longer high-humidity/temperature tests. This is because water and/oroxygen migrated from the resin-sealed portion into the OLED display andimpaired the OLEDs. In contrast, the OLED display according to theembodiment of the present invention did not suffer from deterioration inillumination of the OLEDs and had good test results even in the 7-dayhigh-humidity/temperature test. The result indicated that the OLEDdisplay can maintain good hermeticity. In addition, the OLED displayafter the high-humidity/temperature test was examined to evaluate theadhesion and bonding properties of the seal portion and was found tooffer not so significant deterioration as compared with the resin-sealedOLED display and to have adhesion and bonding properties similar tothose before the test.

As above, the organic light-emitting diode (OLED) display has beendescribed in this experimental example representatively as aglass-sealed component according to an embodiment of the presentinvention. Specifically, the low-temperature sealing glass frit andcorresponding low-temperature sealing glass paste each containing thelead-free low-melting glass composition according to the embodiment ofthe present invention were applied to the OLED display. The resultsdemonstrated that the low-temperature sealing glass frit andcorresponding low-temperature sealing glass paste each containing thelead-free low-melting glass composition according to the embodiment ofthe present invention can be effectively applied to a seal portion of aglass-sealed component and provides a glass-sealed component having highfunctions including reliability and being obtained with excellentproductivity. In addition, the results of the experimental exampleobviously demonstrate that the glass frit and corresponding glass pastecan also be expanded into glass-sealed components that are susceptibleto thermal damage. Such glass-sealed components are exemplified bylighting apparatuses bearing OLEDs; and organic solar cells.

Experimental Example 8

In this experimental example, a solar cell including silicon (Si)substrates having pn bonding was prepared representatively as anelectrical/electronic component according to an embodiment of thepresent invention. Whether and how a conductive material according to anembodiment of the present invention is applicable toelectrodes/interconnections of the solar cell was examined andevaluated. The conductive material in this experimental example wasformed using a conductive glass paste.

FIG. 18A is a schematic view of a light-receiving surface (frontsurface) of the prepared solar cell. FIG. 18B is a schematic view of therear surface (backside) of the solar cell. FIG. 18C is a cross-sectionalview taken along the line A-A of FIG. 18A.

As illustrated in FIG. 18A, the solar cell includes frontelectrodes/interconnections 28 and an antireflection film 31 on thelight-receiving surface of the silicon substrate (Si substrate) 27.

As illustrated in FIG. 18B, the solar cell includes a collectorelectrode/interconnection 29 and output electrodes/interconnections 30on the rear surface.

As illustrated in FIG. 18C, the solar cell includes a pn junction 181adjacent to the light-receiving surface of the silicon substrate 27. Thefront electrodes/interconnections 28, collectorelectrode/interconnection 29, and output electrodes/interconnections 30are formed using the conductive material according to the embodiment ofthe present invention. A conventional solar cell has been prepared inthe following manner. Front electrodes/interconnections 28 and outputelectrodes/interconnections 30 are formed using a lead-containingconductive glass paste containing silver (Ag) particles andlead-containing low-melting glass composition particles. A collectorelectrode/interconnection 29 is formed using a lead-containingconductive glass paste containing aluminum (Al) particles andlead-containing low-melting glass composition particles. Theselead-containing conductive glass pastes are applied to the both sides ofa silicon substrate 27 typically by a screen process printing, dried,fired at 500° C. to 800° C. in the air, and yieldelectrodes/interconnections on the both sides of the silicon substrate27. Unfortunately, the conventional solar cell not only containshazardous lead, but also has various disadvantages as follows.Typically, such high-temperature firing to form theelectrodes/interconnections causes the solar cell to warp significantlyand thereby causes the silicon substrate 27 to be susceptible to failure(breakage). The high-temperature firing also induces a reaction betweenAl in the collector electrode/interconnection 29 and Ag in the outputelectrodes/interconnections 30 to form brittle intermetallic compounds.The brittle intermetallic compounds, if receiving stress in a focusedmanner, may cause the silicon substrate 27 to be susceptible to defectssuch as cracks.

In this experimental example, the silicon substrate 27 including the pnjunction was a solar-cell-use single-crystal silicon substrate having asize of 150 by 150 by 0.2 mm. In addition, a silicon nitride (SiN)antireflection film 31 was formed on the light-receiving surface of thesilicon substrate 27. The antireflection film 31 had a thickness ofabout 100 nm. The front electrodes/interconnections 28 and the outputelectrodes/interconnections 30 were formed using a conductive material.The conductive material contained the lead-free low-melting glasscomposition VTA-01 (see Table 1) and spherical silver (Ag) particleshaving an average particle diameter of about 1.5 μm in a blending ratioin volume percent of 15:85. The collector electrode/interconnection 29was formed using another conductive material. This conductive materialcontained the lead-free low-melting glass composition VTA-02 (seeTable 1) and spherical aluminum (Al) particles having an averageparticle diameter of about 3 μm in a blending ratio in volume percent of10:90.

(Preparation of Conductive Glass Paste)

The lead-free low-melting glass composition according to the embodimentof the present invention VTA-01 or VTA-02 in the form of particles, thesilver (Ag) or aluminum (Al) metal particles, and a solvent wereblended, mixed, and yielded conductive glass pastes. The conductiveglass paste to form the front electrodes/interconnections 28 and theoutput electrodes/interconnections 30 employed VTA-01 particles havingan average particle diameter of about 1 μm and spherical Ag particleshaving an average particle diameter of about 1.5 μm in a blending ratioin volume percent of 15:85. The solvent used was α-terpineol, added withisobornylcyclohexanol as a viscosity modifier. The conductive glasspaste to form the collector electrode/interconnection 29 employed VTA-02particles having an average particle diameter of about 1 μm andspherical Al particles having an average particle diameter of about 3 μmin a blending ratio in volume percent of 10:90. The solvent used wasα-terpineol, added with isobornylcyclohexanol as a viscosity modifier.Each of the conductive glass pastes had a solids content of about 80mass percent, where the “solids content” refers to the total content ofthe lead-free low-melting glass composition particles and the metalparticles.

(Preparation of Solar Cell)

The solar cell as illustrated in FIGS. 18A to 18C was prepared by amethod that will be described below.

The silicon substrate 27 (150 by 150 by 0.2 mm) used herein bore theantireflection film 31 on the light-receiving surface. Theabove-prepared conductive glass paste containing VTA-01 particles and Agparticles was applied to the light-receiving surface of the siliconsubstrate 27 by a screen process printing and dried at 120° C. to 150°C. This was heated in a tunnel furnace up to 220° C. at a rate oftemperature rise of about 20° C. per minute, held for 10 minutes,further heated up to 280° C. at the same rate of temperature rise asabove, and held for 5 minutes to form the frontelectrodes/interconnections 28 on the light-receiving surface of thesilicon substrate 27. Next, the above-prepared conductive glass pastecontaining VTA-01 particles and Ag particles was applied to the rearsurface of the silicon substrate 27 by the screen process printing anddried at 120° C. to 150° C. The above-prepared conductive glass pastecontaining VTA-02 particles and Al particles was applied by the screenprocess printing and dried at 120° C. to 150° C. This was fired underthe same heating conditions as in the formation of the frontelectrodes/interconnections 28 and thereby formed the collectorelectrode/interconnection 29 and the output electrodes/interconnections30 on the rear surface of the silicon substrate 27. The frontelectrodes/interconnections 28 received two thermal hystereses. Thisallowed the front electrodes/interconnections 28 to have good electricalconnection to the silicon substrate 27. The frontelectrodes/interconnections 28, collector electrode/interconnection 29,and output electrodes/interconnections 30 were formed in the abovemanner and yielded a solar cell according to an embodiment of thepresent invention. In this experimental example, ten solar cells wereprepared in the above manner.

(Evaluation Results of Prepared Solar Cells)

Initially, the ten solar cells prepared in this experimental examplewere visually inspected. As a result, the silicon substrate 27, as wellas the front electrodes/interconnections 28, collectorelectrode/interconnection 29, and output electrodes/interconnections 30formed on the silicon substrate 27, offered no defects such as fractureand cracking, no significant warpage, and no appearance disadvantages.This effect was achieved by the lead-free low-melting glass compositionsaccording to the embodiments of the present invention. Specifically, theelectrodes/interconnections could be formed at a significantly lowtemperature. Next, the prepared ten solar cells were further examinedand found to have electrical connection between the silicon substrate 27and the front electrodes/interconnections 28 and to establish ohmiccontact between the silicon substrate 27 and the collectorelectrode/interconnection 29 and between the silicon substrate 27 andthe output electrodes/interconnections 30. The ten solar cells werefurther examined using a solar simulator to evaluate the generationefficiency. As a result, the solar cells were found to have a generationefficiency of about 18% as high as the generation efficiency ofconventional equivalents, even though the solar cells were prepared at aremarkably low temperature. To determine the reliability, three of theprepared solar cells were immersed in warm water at 50° C. for 5 daysand examined to measure the generation efficiency in a similar manner asabove. The conventional solar cell suffered from corrosion of theelectrodes/interconnections and had significantly lower generationefficiency of about 12% to about 13%. In contrast, the solar cellsprepared in this experimental example little suffered from corrosion ofthe electrodes/interconnections and offered approximately nodeterioration in generation efficiency. This is probably because thespecific reaction of the lead-free low-melting glass compositionaccording to the embodiment of the present invention with Ag or Al cangive solar cells having such high reliability, as described inExperimental Example 4.

Next, an overlap portion of the collector electrode/interconnection 29and the output electrodes/interconnections 30 on the rear surface wasdisintegrated and examined. As a result, the overlap portion was foundto include no brittle intermetallic compound that is formed by thereaction between Ag and Al. Thus, the silicon substrate 27 came toresist defects such as cracking even when receiving stress in a focusedmanner. In addition, the silicon substrate 27 significantly lesssuffered from warpage, and this contributed less failure of the solarcell when handled typically upon assemblage into a module. Thus, thebrittle intermetallic compounds were prevented from forming and thesolar cell less suffered from warpage. This is because the solar cellaccording to the embodiment of the present invention can be fired at asignificantly low temperature (280° C.) as compared with the firingtemperatures (500° C. to 800° C.) of the conventional solar cells.

As above, the solar cell has been described in this experimental examplerepresentatively as an electrical/electronic component according to anembodiment of the present invention. Specifically, the solar cellincluded electrodes/interconnections formed using the conductivematerial and corresponding conductive glass paste each containing thelead-free low-melting glass composition according to the embodiment ofthe present invention. The conductive material and correspondingconductive glass paste each containing the lead-free low-melting glasscomposition according to the embodiment of the present invention can beeffectively applied to electrodes/interconnections of not only suchsolar cells, but also various electrical/electronic components. Theconductive material and corresponding conductive glass paste can provideelectrical/electronic components that have higher functions such asreliability and excel typically in productivity and yield.

Experimental Example 9

In this experimental example, a quartz resonator package was preparedrepresentatively as an electrical/electronic component according to anembodiment of the present invention. Whether and how the conductivematerial and the low-temperature sealing glass frit according toembodiments of the present invention are applicable to conductivejunctions and/or seal portions of the package was examined andevaluated. In this experimental example, the conductive material and thelow-temperature sealing glass frit were formed respectively using aconductive glass paste and a low-temperature sealing glass paste.

FIGS. 19A to 19F illustrate how to prepare the quartz resonator package.FIG. 19G is a schematic cross-sectional view of the prepared quartzresonator package.

The quartz resonator package illustrated in FIG. 19G includes a ceramicsubstrate 33 and a quartz resonator 32. The ceramic substrate 33includes interconnections 34. The quartz resonator 32 is disposed overthe ceramic substrate 33 via conductive junctions 35. Theinterconnections 34 and the conductive junctions 35 are electricallyconnected to each other. This allows the quartz resonator 32 to beelectrically connected to the outside. The package further includes aceramic cap 36 to protect the quartz resonator 32. The ceramic cap 36 ishermetically bonded to a peripheral portion of the ceramic substrate 33in the seal portion 37. The conductive junctions 35 are formed using theconductive material according to the embodiment of the presentinvention, and the seal portion 37 is formed using the low-temperaturesealing glass frit according to the embodiment of the present invention.

The quartz resonator package is prepared in the following manner.

Initially, the ceramic substrate 33 bearing the interconnections 34 isprepared (FIG. 19A). Next, the conductive glass paste is applied ontothe interconnections 34, dried, heated in the air or in an inert gas toallow the lead-free low-melting glass composition in the conductiveglass paste to soften and flow to thereby form the conductive junctions35 (FIG. 19B).

The quartz resonator 32 is arranged on the conductive junctions 35 (FIG.19C), heated in an inert gas or in a vacuum to allow the lead-freelow-melting glass composition in the conductive junctions 35 to softenand flow again to thereby establish electric connection.

Independently, the ceramic cap 36 is prepared (FIG. 19D). Thelow-temperature sealing glass paste is applied to a peripheral portionof the ceramic cap 36 (FIG. 19E), dried, and heated in the air to allowthe lead-free low-melting glass composition in the low-temperaturesealing glass paste to soften and flow to thereby form the seal portion37.

The ceramic substrate 33 bearing the quartz resonator 32 and theconductive junctions 35 (see FIG. 19C) is arranged as illustrated inFIG. 19F to face the ceramic cap 36 including the seal portion 37 (seeFIG. 19E) and heated in an inert gas or in a vacuum while applying someload 38 to allow the lead-free low-melting glass composition in the sealportion 37 to soften and flow again. This gives the quartz resonatorpackage (FIG. 19G).

The process may be performed carefully so as to prevent the conductivejunctions 35 from separating from the quartz resonator 32 and theinterconnections 34. For this reason, the ceramic cap 36 and the ceramicsubstrate 33 are preferably sealed at a temperature equal to or lowerthan the softening point of the lead-free low-melting glass compositionin the conductive junctions 35. Specifically, the lead-free low-meltingglass composition to be contained in the low-temperature sealing glasspaste preferably differs from, and has a softening point lower than, thelead-free low-melting glass composition to be contained in theconductive glass paste. The two lead-free low-melting glass compositionsmay have a difference in softening point between them of 20° C. orhigher, and preferably 40° C. or higher.

(Preparation of Conductive Glass Paste and Low-Temperature Sealing GlassPaste)

In this experimental example, the lead-free low-melting glasscomposition to be contained in the conductive glass paste was VTA-16having a softening point of 280° C. (see Tables 2 and 3); and thelead-free low-melting glass composition to be contained in thelow-temperature sealing glass paste was VTA-33 having a softening pointof 240° C. (see Tables 2 and 3). VTA-16 and VTA-33 have a difference insoftening point of 40° C. and enable sealing without problems such asseparation of the conductive junctions 35. This means that theconductive junctions 35 and seal portion 37 both at satisfactorilylevels can be obtained at once.

Initially, particles of a lead-free low-melting glass compositionaccording to an embodiment of the present invention, metal particles,and a solvent were blended, mixed, and yielded the conductive glasspaste for the formation of the conductive junctions 35. The lead-freelow-melting glass composition particles used herein were VTA-16particles having an average particle diameter of about 3 μm; the metalparticles were spherical silver (Ag) particles having an averageparticle diameter of about 1.5 μm; and the solvent was α-terpineol. Thepaste was further added with isobornylcyclohexanol as a viscositymodifier. The VTA-16 particles and the Ag particles were blended in aratio in volume percent of 30:70. The conductive glass paste wasprepared so as to have a solid content of about 80 mass percent, wherethe “solids content” refers to the total content of VTA-16 and Ag.

Separately, particles of a lead-free low-melting glass compositionaccording to an embodiment of the present invention,low-thermal-expansion ceramic particles, and a solvent were blended,mixed, and yielded the low-temperature sealing glass paste for theformation of the seal portion 37. The lead-free low-melting glasscomposition particles used herein were VTA-33 particles having anaverage particle diameter of about 3 μm; the low-thermal-expansionceramic particles were CF-01 (zirconium phosphate tungstate) particleshaving an average particle diameter of about 10 μm (see Table 4); andthe solvent was α-terpineol. The paste was further added withisobornylcyclohexanol as a viscosity modifier. The VTA-33 particles andthe CF-01 particles were blended in a ratio in volume percent of 70:30.The low-temperature sealing glass paste was prepared so as to have asolids content of about 80 mass percent, where the “solids content”refers to the total content of VTA-33 and CF-01.

(Preparation of Quartz Resonator Package)

The quartz resonator package was prepared in this experimental exampleby a method that will be illustrated specifically below. The ceramicsubstrate 33 and the ceramic cap 36 used in this experimental examplewere both made of aluminum oxide (α-Al₂O₃).

The prepared conductive glass paste was applied onto theinterconnections 34 in the ceramic substrate 33 by dispensing and driedat 120° C. to 150° C. in the air (FIGS. 19A and 19B). This was heated upto 220° C. at a rate of temperature rise of 20° C. per minute in theair, held for 20 minutes, heated up to 330° C. at the same rate oftemperature rise as above, and held for 10 minutes to form theconductive junctions 35 on the interconnections 34 of the ceramicsubstrate 33. The heating temperature 330° C. is higher than thesoftening point of VTA-16 by 50° C.

Next, the quartz resonator 32 was arranged on the formed conductivejunctions 35, heated up to 330° C. at a rate of temperature rise of 20°C. per minute in an inert gas (argon), and held for 10 minutes toconnect the quartz resonator 32 to the conductive junctions 35 (FIG.19C).

Independently, the prepared low-temperature sealing glass paste wasapplied to the peripheral portion of the ceramic cap 36 by the screenprocess printing and dried at 120° C. to 150° C. in the air (FIGS. 19Dand 19E). This was heated up to 220° C. at a rate of temperature rise of10° C. per minute in the air, held for 20 minutes, further heated up to280° C. at the same rate of temperature rise as above, and held for 10minutes to form the seal portion 37 in the peripheral portion of theceramic cap 36. The heating temperature of 280° C. is higher than thesoftening point of VTA-33 by 40° C.

The ceramic cap 36 bearing the seal portion 37 was arranged so as toface the ceramic substrate 33 connected to the quartz resonator 32. Theresulting article was placed in a dedicated fixture and applied with aload (FIG. 19F). This was heated up to 280° C. at a rate of temperaturerise of 10° C. per minute in a vacuum, held for 10 minutes to seal theceramic cap 36 and the ceramic substrate 33, and yielded the quartzresonator package (FIG. 19G). In this experimental example, twenty-fourquartz resonator packages were prepared in the above manner.

(Evaluation Results of Prepared Quartz Resonator Packages)

Initially, eighteen of the quartz resonator packages prepared in thisexperimental example were visually inspected using a stereoscopicmicroscope. As a result, the packages offered little misregistration ofthe ceramic cap 36 upon sealing, did not offer defects such asdenitrification due to crystallization, fracture, and cracking in theseal portion 37, and had no defects in appearance.

Next, whether the conductive junctions 35 in the sealed ceramic cap 36was electrically connected to the quartz resonator 32 and to theinterconnections 34 was examined by a conduction test from theinterconnections 34 on the rear surface of the ceramic substrate 33. Theresults verified that the quartz resonators went into action in all theprepared quartz resonator packages. In addition, five of the preparedquartz resonator packages were subjected each to a helium leak test andwere found that the package inside was maintained under vacuum, and theperipheral portion was hermetically sealed with the seal portion 37. Toverify the reliability of the seal portion 37, five of the preparedquartz resonator packages were each subjected ahigh-humidity/temperature test (saturated pressure cooker test) at 120°C., 100% relative humidity, and 202 kPa for 3 days. The samples weresubjected to the helium leak test again and were found that all thequartz resonator packages after the high-humidity/temperature testmaintained the hermeticity and adhesion of the seal portion 37.

The results demonstrated as follows. Assume that a conductive materialand/or a corresponding conductive glass paste each containing alead-free low-melting glass composition according to an embodiment ofthe present invention is applied to a conductive junction; and that alow-temperature sealing glass frit and/or a correspondinglow-temperature sealing glass paste each containing a lead-freelow-melting glass composition according to an embodiment of the presentinvention is applied to a seal portion. This can give quartz resonatorpackages that have high reliability after consideration of influence onthe environmental burden. In this experimental example, the conductivematerial and others are applied to a quartz resonator packagerepresentatively as an electrical/electronic component and aglass-sealed component according to an embodiment of the presentinvention. Obviously, however, the conductive material and correspondingconductive glass paste, low-temperature sealing glass frit, andcorresponding low-temperature sealing glass paste according toembodiments of the present invention can be effectively expanded notonly into such quartz resonator packages, but also into many ofelectrical/electronic components and glass-sealed components eachincluding a conductive junction and/or a seal portion.

In Experimental Examples 6 to 9, the vacuum-insulating double glasspanels, OLED displays, solar cells, and quartz resonator packages havebeen described representatively as glass-sealed components andelectrical/electronic components according to embodiments of the presentinvention. Obviously, however, the present invention is not limited tothese examples and can be applied to many of glass-sealed components andelectrical/electronic components such as image display devices, personaldigital assistants, IC ceramic packages, semiconductor sensors,multilayer capacitors, LEDs, and multilayered circuit boards.

What is claimed is:
 1. A lead-free low-melting glass compositioncomprising: a principal component; and an additional component, theprincipal component comprising vanadium oxide, tellurium oxide andsilver oxide, and the additional component comprising at least onesubstance selected from the group consisting of yttrium oxide andlanthanoid oxides, wherein the additional component comprises 0.1 to 3.0mole percent oxide.
 2. The lead-free low-melting glass compositionaccording to claim 1, wherein the additional component comprises atleast one substance selected from the group consisting of Y₂O₃, La₂O₃,CeO₂, Er₂O₃ and Yb₂O₃, and wherein the percent oxide in the additionalcomponent is 0.1 to 2.0 mole percent.
 3. The lead-free low-melting glasscomposition according to claim 1, wherein the principal componentcomprises a total content of V₂O₅, TeO₂, and Ag₂O of 85 mole percent ormore in terms of oxide, and wherein the TeO₂ and the Ag₂O are each at acontent of 1 to 2 times the content of V₂O₅.
 4. The lead-freelow-melting glass composition according to claim 3, further comprisingat least one selected from the group consisting of BaO, WO₃ and P₂O₅,wherein a total content of BaO, WO₃ and P₂O₅ is 13 mole percent or lessin terms of oxide.
 5. The lead-free low-melting glass compositionaccording to claim 1, wherein the glass composition has a softeningpoint of 280° C. or lower, the softening point being determined as asecond endothermic peak temperature by a differential thermal analysis.6. The lead-free low-melting glass composition according to claim 5,having a crystallization onset temperature higher than the softeningpoint by 60° C. or more, the crystallization onset temperature beingdetermined by the differential thermal analysis.
 7. A low-temperaturesealing glass frit comprising: the lead-free low-melting glasscomposition according to claim 1; and low-thermal-expansion ceramicparticles, wherein the lead-free low-melting glass composition is at 40or more volume percent and less than 100 volume percent in thelow-temperature sealing frit, and the low-thermal-expansion ceramicparticles is at greater than 0 volume percent and 60 or less volumepercent in the low-temperature sealing frit.
 8. The low-temperaturesealing glass frit according to claim 7, wherein thelow-thermal-expansion ceramic particles comprise at least one substanceselected from the group consisting of zirconium phosphate tungstate(Zr₂(WO₄)(PO₄)₂), quartz glass (SiO₂), zirconium silicate (ZrSiO₄),aluminum oxide (Al₂O₃), mullite (3Al₂O₃.2SiO₂) and niobium oxide(Nb₂O₅).
 9. A low-temperature sealing glass paste comprising: particlesformed of the lead-free low-melting glass composition according to claim1; low-thermal-expansion ceramic particles; and a solvent.
 10. Thelow-temperature sealing glass paste according to claim 9, wherein thelow-thermal-expansion ceramic particles include at least one substanceselected from the group consisting of zirconium phosphate tungstate (Zr₂(WO₄) (PO₄)₂), quartz glass (SiO₂), zirconium silicate (ZrSiO₄),aluminum oxide (Al₂O₃), mullite (3Al₂O₃.2SiO₂) and niobium oxide(Nb₂O₅), and wherein the solvent includes at least one of α-terpineoland diethylene glycol n-butyl ether acetate.
 11. A conductive materialcomprising: the lead-free low-melting glass composition according toclaim 1; and metal particles, wherein the lead-free low-melting glasscomposition is 5 or more volume percent and less than 100 volume percentof the conductive material, and the metal particles are greater than 0volume percent and 95 or less volume percent of the conductive material.12. The conductive material according to claim 11, wherein the metalparticles include at least one substance selected from the groupconsisting of silver (Ag), silver alloys, copper (Cu), copper alloys,aluminum (Al), aluminum alloys, tin (Sn) and tin alloys.
 13. Aconductive glass paste comprising: particles formed of the lead-freelow-melting glass composition according to claim 1; and a solvent. 14.The conductive glass paste according to claim 13, further comprisingmetal particles.
 15. The conductive glass paste according to claim 13,wherein the solvent includes at least one of α-terpineol and diethyleneglycol n-butyl ether acetate.
 16. A glass-sealed component having a sealportion including 40 to 100 volume percent of a lead-free low-meltingglass phase, wherein the lead-free low-melting glass phase comprises aprincipal component including a vanadium oxide, a tellurium oxide and asilver oxide, and an additional component comprising at least oneselected from the group consisting of yttrium oxide and lanthanoidoxides, and the additional component is 0.1 to 3.0 mole percent of thelead-free low-melting glass phase.
 17. The glass-sealed componentaccording to claim 16, wherein the lead-free low-melting glass phasecomprises the principal component in a total content of 85 mole percentor more in terms of oxide, and the TeO₂ and Ag₂O are each at 1 to 2times the content of V₂O₅, and wherein the additional componentcomprises at least one selected from the group consisting of Y₂O₃,La₂O₃, CeO₂, Er₂O₃, and Yb₂O₃, and the additional component is 0.1 to2.0 mole percent of the lead-free low-melting glass phase, and whereinthe lead-free low-melting glass phase further comprises a secondarycomponent comprising at least one substance selected from the groupconsisting of BaO, WO₃ and P₂O₅, and a total content of the secondarycomponent is 13 mole percent or less of the lead-free low-melting glassphase in terms of oxide.
 18. The glass-sealed component according toclaim 16, being one of a vacuum-insulating double glass panel and adisplay panel.
 19. An electrical/electronic component comprising atleast one unit selected from the group consisting of electrodes,interconnections, and conductive junctions, wherein the unit includes 5to 100 volume percent of a lead-free low-melting glass phase, and 0 to95 volume percent of metal particles, the lead-free low-melting glassphase comprising a principal component and an additional component, theprincipal component comprising a vanadium oxide, a tellurium oxide, anda silver oxide, the additional component comprising at least oneselected from the group consisting of yttrium oxide, and lanthanoidoxides, the additional component being 0.1 to 3.0 mole percent of thelead-free low-melting glass phase, the metal particles comprising atleast one substance selected from the group consisting of silver (Ag),silver alloys, copper (Cu), copper alloys, aluminum (Al), aluminumalloys, tin (Sn) and tin alloys.
 20. The electrical/electronic componentaccording to claim 19, wherein the principal component is at 85 molepercent or more in terms of V₂O₅, TeO₂, and Ag₂O in the lead-freelow-melting glass phase, wherein the TeO₂ and Ag₂O are each at 1 to 2times as much as the content of V₂O₅, wherein the additional componentcomprises at least one selected from the group consisting of Y₂O₃,La₂O₃, CeO₂, Er₂O₃, and Yb₂O₃, wherein the additional component is at0.1 to 2.0 mole percent of the lead-free low-melting glass phase, andwherein the lead-free low-melting glass phase further comprises asecondary component comprising at least one substance selected from thegroup consisting of BaO, WO₃, and P₂O₅, the secondary component being 13mole percent or less in terms of oxide in the lead-free low-meltingglass phase.